Servers usually have to pay in X% of their total sales to the back of house. So if you stiff me on a $90 check, i lose $3 because i still have to pay that much in. I actually had a slow night where bith tables stiffed me so i actually left the restaurant $4 poorer than when i entered. Because ihad a better night the next shift, the owner was able to average me out so that he didn’t have to pay me more than the server minimum wage.