Yes, this isn't a question about the US or Europe.

Some of the absolute worst service I've received have been in the US, yet they ask for tips. I've also received some of the best service at a US restaurant, where the suggested tip was 10% and the prices where pretty low.

The weirdest thing I've experience is the large number of staff in US coffee shops, compared to locally, yet basically not being able to order, and then having a suggested tip at 20%. I've encountered this a multiple locations, and different chains. Four people, one person takes the order, one makes the drink, one continuously mop the floor and the last person just stands around (manager?) You could significantly increase the base pay by getting rid of two of these people.