In some countries you do.
When my grandpa was in the hospital towards the end of his life, the nurses let him lay in his own piss for half a day before doing anything about it. We gave them an envelope with a generous "tip", and after that they started paying much closer attention to my grandpa.
Many people give a few thousand USD cash to the midwife and the doctor after delivering their baby.
which country is this? you tip all service staff? are you presenting me a logically coherent tipping culture or just another version of the american righteousness?
The line between bribing and tipping isn't that thin.