Mother-of-two Emily Bauer hoped to "splurge" on Christmas for her two young boys, but says her employee told her it is not able to process payments of more than $500.
In a blog post, CEO Tony Xu said that the company would no longer use the tip money to cover drivers' base pay.
The suspect made "bizarre statements about giving away his child on Facebook," an arrest affidavit said.
Service workers' mental health could be negatively impacted by "the customer is always right" mentality, researchers said.
Think more than 20 percent is too much? Try 800,000 percent on for size.
Tipping encourages a willingness to please by waiters that would be out of place in a European restaurant.