Here in the states there is a miminum wage law. Employees have to be paid a certain amount "EXCEPT" certain service workers, like wait staff, bartenders & the like, it doesn't matter if their employer is cheap or not, they get & are expected to get tip on their service/performance. They can get paid far less per hour than the mininum because they rely legally on tips

That's certainly true for the US, and is probably the reason most UK people don't like the practise. The idea of "a fair days work for a fair days pay" has a very strong history here. Added to which the idea that a service is quoted as xyz but we all know it is 'really' going to cost xyz+10% for tips grates.

[True story as an aside: The first time I went to the US was on business and my boss told me to tip everything at 10%-15%. "Everything?" I asked. "Everything", he confirmed. "Don't try to understand it, just do it. It's the American way."

When I left the hotel after a fortnight's stay the receptionist was very pleased with her tip of a few hundred dollars. My boss, less so.]