Leaving a pleasant note of encouragement or a decent tip may be enough to turn their day around.
No way, leave a loonie or a penny and there is no mistaking that they need to pick up their game. However if you work in the service industry and don’t bring your A-game then you deserve to be reminded in the wallet. I don’t know of any other jobs apart from civil service where you can be rewarded for not actually doing a good job.
I know it’s a hard stance but just think about the number of times you have been chewed out for missing a deadline or not catching the error before it went out. If your daily motivation is being patted on the back by strangers who think they know you then you need to re-evaluate what your doing and why you are still doing it.