Why don’t more tech companies offer on-site child care?

They can afford it.

Apple, one of the wealthiest American companies with around 110,000 employees, has a new corporate campus that reportedly cost an estimated $5 billion. The main office has every perk imaginable, including custom-made pizza boxes, a “fitness and wellness center” that takes up 100,000 square feet, and sliding glass doors that extend along the four stories of the cafeteria and are operated via some sort of silent underground mechanism. “Why do you need a four-story sliding glass door?” Wired’s Steven Levy asks veteran Apple designer Johnny Ive. “Well, it depends on how you define need,” Ive says, “doesn’t it?”

There is one luxury Apple declined to provide, which Quartz astutely picked up on. It is the ultimate in workplace luxury, guaranteed to keep employees happily working long hours. It’s also one of the most effective ways to retain women. So when Apple was designing its worker paradise, why did it skip the on-site child care?

We should start by saying that Apple is not obligated to provide this perk. On-site day care is extremely rare; by The Outline’s count, only 17 of the Fortune 100 top companies provide at least one on-site child care center. Apple did not respond to questions about employee benefits, but it reportedly does a lot to support parents of young children, including a fairly generous maternity and paternity leave policy; as of 2014, expectant mothers could take four weeks prior to delivery and 14 after, with other parents able to take six weeks. And of course, the job pays pretty well. At the end of the day, Apple employees are not the type of people who are most burdened by high child care costs.

However, Apple is a trend setter and a marquee tech company, and it’s fair to ask why its generosity — Wired’s fawning cover story emphasized that no expense was spared in the building of this campus — stops at on-site daycare. And it’s not just Apple. Silicon Valley has always been Wall Street’s nerdier cousin: the hours are grinding, the culture is heavily white and male, and the profits can be magnificent. But while Wall Street’s perks come in the form of boozy parties and heady bonuses, tech companies built offices that were like adult wonderlands, with scooters and yoga and endless snacks. Dropbox has haircuts and gym laundry on campus. Amazon’s got tree houses. Asana gives its employees $10,000 to customize their workspaces. Googlers get free massages and can bring their dogs to work basically whenever. And given that we live in a time when your boss can email you at 8 p.m. and expect a response, is it so crazy to ask that a company might try to make it possible for you to see your kid during your lunch break?

What does it take to provide on-site daycare? One estimate put the cost of taking over an already existing facility that can serve 80 kids at around $30,000, and that’s without significant construction costs. Building and outfitting a new facility on the site of a corporate campus to care for the same number of kids could cost more than $400,000, based on average construction costs, physical requirements of child care centers, and associated costs.

There are also legal costs, and liability insurance is a must. State regulations like the amount of caregivers per kid, specific training, storage of materials, and more must be met or the company could be fined. To top it off, companies might want make sure an on-site center can scale with their workforce if they’re not looking to renovate on a regular basis. While capital isn’t really a problem for Apple or the other major tech companies, these costs can add up fast.

In California, where Apple and most of its over-the-top-perk-giving brethren are based, child care centers must conduct background checks for everyone and an inspection of the facility to ensure it meets the standards associated with the age group it will serve, according to Michael Weston, deputy director of public affairs and outreach programs at the California Department of Social Services. Beyond that, the requirements change depending on what kind of kids are going to be in the center. “There’s a license for providing care to infants,” Weston said, “there’s a license for providing care to children age two to five, and then there’s a license for providing care to children who are over the age of five and school age.” The requirements for each are not the same, though the same facility could theoretically meet all of them if large enough, and the licenses aren’t prohibitively expensive.

A 2016 report about the cost of child care from Child Care Aware of America, a nonprofit organization focused on and advocating for affordable, high-quality child care, points to companies like Dow Jones, Johnson & Johnson, and Prudential as examples of those with some form of on-site child care at certain campuses, with Johnson & Johnson being the most prevalent with six on-site centers. Home Depot is another example of significant investment in on-site child care.

Apparel brand Patagonia is likely the best known example of those companies with on-site child care, and in part that’s thanks to the marketing push behind the effort that includes a book, Family Business, about its efforts in on-site child care dating back to 1983. Patagonia CEO Rose Marcario claimed in an article adapted from the book that the company recoups about 91 percent of $1 million dollars in annual costs — a number which comes out to about $12,500 dollars per kid — thanks to savings associated with the likes of tax breaks and not having to replace parents who leave the workforce to care for their kids.

Exact figures for how many employers offer on-site child care are not available, but Jennifer Sabatini Fraone, director of corporate partnerships at the Boston College Center for Work & Family, which conducts research on how companies can be more supportive of employees, estimated it’s between 4 and 8 percent.

“A lot of times many places aren’t able to do on-site child care,” said Dionne Dobbins, senior director of research at Child Care Aware of America. She estimated that around 7 percent of employers offer on-site child care. “It’s a luxury, I would say.”

Dobbins pointed to the 2016 National Study of Employers by the Society for Human Resource Management and Families and Work Institute, saying that it indicates most employers know child care is important, but they commonly offer some sort of plan where pre-tax dollars can be used for child care or offer help with locating local child care instead (Facebook does a version of this by subsidizing day care and offering $4,000 in cash to new parents). However, on-site day care is still rare, and understandably even more rare outside of top 100 companies.

In fact, child care benefits in general are not the norm. Only 10 percent of American workers in private industry have access to some form of child care benefit according to a 2016 report by the Bureau of Labor Statistics, which defined a “child care” benefit as any “workplace program that provides for either the full or partial cost of caring for an employee’s children in a nursery, day care center, or a baby sitter in facilities either on or off the employer’s premises.” That number doubles for those jobs in the top 25 percent in terms of average wages, and it almost triples to 29 percent for those companies with 500 or more employees.

Why do people keep bringing up on-site child care when it is in fact so rare? Child care benefits, and more specifically the use of on-site centers, has a huge impact on retention of new parents and especially women. Patagonia, for example, reportedly had a retention rate of 100 percent for mothers coming back to work after giving birth over a five-year period as of 2016. The top 10 companies from the 2016 Working Mother 100 Best Companies all offer some kind of child care assistance, with several having on-site care.

And when it comes to Silicon Valley companies, the statistics for hiring women and retention rates associated with them are overwhelmingly bad. About 30 percent of the tech industry is reportedly made up of women, and yet, according to one study, almost 40 percent of women with engineering degrees either leave or never enter the field. Changing the work environment, the study concludes, is imperative in order to retain these women, and that includes offering options like child care.

In an industry where women are still fighting for equal status — in April, Google was accused of “extreme” gender discrimination in pay by the Department of Justice — offering on-site day care sends a strong message that women are valued.

As of last year, 24 of Fortune’s 100 Best Companies to Work For offered some kind of on-site care. Why not tech companies that pay lip service to gender diversity and retaining women in the workforce? Apple, the most profitable company in the United States, can certainly afford it. Running on-site child care sounds like a logistical nightmare, but then, so does operating iTunes.