Tipping is a custom -- not a mandatory form of wealth or income redistribution -- and tipping is practiced less worldwide than in years past. In fact, the US is one of the holdouts to practice this rather old custom.

Everyone except bartenders and waiters in the US is required by law to be paid a legal wage. If not, that is a serious crime that is a matter between the local DA's office and the employer.

Bartenders and waiters alone receive a sub-minimum wage. Because of that fact, I support the custom of the 15% tip on food service and a customary drinks tip to the bar ($1 per drink is customary in New England).

Above and beyond that, the tipping situation quickly spins out of control.

If you receive special personal service from someone regardless of job code, by all means you are welcome to tip. In fact, anyone is free to tip anyone, or to give money to anyone on the street for example. But it is not a US tradition nor a historical fact nor a worldly requisite to hand out money except as per custom.