I agree waiters and waitresses have set expectations because you're indeed sharing the cost of employing them. However it's not clear to me if the manager at <

I agree waiters and waitresses have set expectations because you're indeed sharing the cost of employing them. However it's not clear to me if the manager at <random coffee shop> is paying the guy running a cash register $2-$3/hr and expecting tips to make up the balance or not. Running a register and handing people their order from behind a counter are not traditionally roles that expect or receive tips.