Earlier quoted context omitted.
In some cultures, people "tip" teachers, police officers, doctors, politicians, judges... you know where I'm going with that... I'm not saying tips should be banned but there certainly is a "cultural aspect" to tipping...
No, they don't. You're trying a false equivalency between a bribe and gratuity. A bribe happens before the service is provided and the service is contingent upon the bribe. Gratuity is post factum, technically based on the quality of the service provided.
In more egregious instances in food service I saw employees trade goods for tips quid-pro-quo and cut the business entirely out of the transaction.