fsm said:

The Fair Labor Standards Act (FLSA) requires payment of at least the Federal minimum wage to covered, nonexempt employees. An employer of a tipped employee is only required to pay $2.13 an hour in direct wages if that amount plus the tips received equals at least the Federal minimum wage, the employee retains all tips and the employee customarily and regularly receives more than $30 a month in tips. If an employee’s tips combined with the employer’s direct wages of at least $2.13 an hour do not equal the Federal minimum hourly wage, the employer must make up the difference.

https://webapps.dol.gov/elaws/faq/esa/flsa/002.htm

They seemingly are accepting of this as well, I mean it reads like outright exploitation