Might fit under fraud. I hope it does. When I first learned of this tactic, I felt tricked. I assumed with a tip, that I was boosting someone’s salary for a job well done. I’m sure it’s debatable, and that my assumption was wrong? But I imagine most people feel this what a tip is.

Fraud n. the intentional use of deceit, a trick or some dishonest means to deprive another of his/her/its money, property or a legal right.

Yes. Washington State law is explicit about this.

RCW 49.46.020 section 3:

"Tips and service charges paid to an employee are in addition to, and may not count towards, the employee's hourly minimum wage."

Source: https://app.leg.wa.gov/RCW/default.aspx?cite=49.46.020