My answer to this is biased by the fact that I know people getting paid under the fed. min. wage when tips are included. I don’t think anyone should be paid under that number for an hour of work, and I’ve seen it happen firsthand in many different industries, food service included.
My source is first hand, talking to Sonic Carhops in TX, but that was back in 2008. My current source is this: https://www.glassdoor.com/Hourly-Pay/Sonic-Hourly-Pay-E1303.htm
Which shows a range of $2-$11 for that position. The $11 are probably CA employees.