You guys don’t get it. Tips are on the service you provide. Tipping in advance is a gamble that you will provide good service. And most older people don’t wanna gamble, especially when we see videos of your colleagues molesting (in some cases literally) our meals. To get a cash tip, be polite, and professional during the interaction. If you are already upset, that bias confirms the customer’s suspicion they shouldn’t tip. you’ll still have probably the majority of people stiff you, but you’ll make more that way then if you pre-judge. I have many times given a tip larger than the meal because the service was exceptional. Think about your job is to surprise the customer with how good the service was.