This pregnant waitress was saved by a $900 tip, but that's not how it should be.

For seven years, Sarah Clark has worked as a waitress and bartender at Pita Jungle in Phoenix, Arizona.

It's the kind of place where people order hummus plates, gyros, and maybe a couple of beers. The work keeps Clark on her feet all day, and now that she's nine months pregnant, it's the kind of job that she needs even more, with her baby due on Jan. 8, 2017.

Like far too many expectant parents in this country, Clark won't have any income after her baby is born. To make matters worse, her husband is out of work and about to undergo surgery for a leg injury. As reported by local CBS station KPHO, Clark has been working as much as she can, to make extra tips, at a time when many doctors recommend women stay off their feet.

But suddenly, a little bit of generosity arrived just in time.

A customer she'd see a few times before — a woman who is also pregnant — had left her an unusual tip after picking up a takeout order. Looking down at the thin slip of paper, it must have  looked like a mistake — a $900 tip on an order of $61.30.

"Nine hundred dollars is a lot of money. It took a while for it to set in, and once it did I cried," she said.

"You always hear about these happening, but you never expect to be the recipient of it," Clark told KPHO. "It’s a huge, huge help for me and my family."

While the kind stranger in this story should be applauded for her generosity, no working family's financial security should depend on a random act of kindness.

The United States is one of a small handful of industrialized countries that does not offer paid maternity leave.

Things are particularly bleak in the service industry. According to Bloomberg, only 6% of service workers (such as waiters and sales clerks) get any paid leave at all. So time spent recovering from birth, bonding with your child, and adjusting to parenthood is limited by what you can afford.

On top of that, Clark works a tip-based job. So her employers are legally allowed to pay her well below the minimum hourly wage, expecting that her tips will make up for it.  

However, we can celebrate the U.S. companies that have recently offered paid parental leave in an attempt to catch up to the rest of the world.

Netflix announced in 2015 that it would give employees up to 12 months of parental leave to their salaried employees, and IKEA recently announced a four-month paid leave policy for its U.S. employees. Company by company and state by state, employers and lawmakers are beginning to recognize the necessity for paid parental leave.

It's not just a convenience either. It's the right thing to do for families and businesses.

Paid leave for new parents has been shown to improve employee retention at companies and reduce the need for public assistance like food stamp programs. When Google increased their paid maternity leave from 12 to 18 weeks, they noticed the benefits quickly:

"Mothers were able to take the time they needed to bond with their babies and return to their jobs feeling confident and ready," wrote YouTube CEO Susan Wojcicki in an op-ed. "And it's much better for Google's bottom line — to avoid costly turnover, and to retain the valued expertise, skills, and perspective of our employees who are mothers."

Clark was lucky to serve such a generous customer, but her ability to comfortably raise a child shouldn't be a Christmas miracle. It should be the least she could ask for.