the wait staff would be getting a reduced minimum wage(https://labor.mo.gov/DLS/MinimumWage/tipped) with the remaining made up for with tips. with this lower min wage the tipped employees would have to make 3.85cents in tips, that's 38dollars of sales an hour if you figure a 10% tip. at $10 the restaurant will have to come up with another $1.15 an hour and the tipped employees will need to have $50 worth of sales an hour.

if you have 3 tables per wait staff and say 2-3 ppl per table in an hour thats 10 sales of $5. outside of SUPER marginal restaurants that wouldnt have 3 additional employees i think they'd be fine. the owners should be working on dividends or flat salary and thus min wage law doesnt really apply. honestly, if your customer volume and avg sales income is so low that you cant hit those marks you probably should be running a food cart/truck or something and not a full retail establishment as even without a $10 min wage law you'd be spending way too high of a % of income on rent.