From my experience that's what Europeans think(or pretend to) but they don't realize(or pretend not to) it's an American custom/tradition to add a 15-20% gratuity for the server depending on quality of service and the tippers personal values.

I have a friend that was a bar manager/bartender at nights and weekends at a local country club and they would sometimes have large golf or tennis events and I would help him behind the bar for some extra cash(running drinks/food,collecting checks, making sure people were happy, if I saw an upset face I was supposed to go see why and if I could fix it). The area we lived in was probably 10-15% people from Europe who can't or won't speak English. They seem to love these country club events that are open to the public if you buy a ticket so they represented about 30% of the few thousand people that would show in a weekend. The Americans would always be fast with their ordering, pay and then leave a gratuity, sometimes less than 20% but it was made up for by the people that would leave $100! bills on $50 orders. Explaining gratuity to the European customers was the hardest part of the job, they'd become belligerent and ramble to try and get out of it and often leave $1 or less on orders of $50+. Granted the food and alcohol at the bar was expensive but these were always events for charity and the course and it's amenities are not open to the public regularly. I'll never forget one German man who bought about $80 worth of mixed drinks and food for himself and his friends, I gave him back his change and he just turned to walk away, I said "excuse me sir, gratuity is not included today as it's a cash bar and it is required according to our rules", he proceeded to take four of the pennies that had been in his change and place them on the bar with a sour look on his face. I didn't even really think before I reacted but I picked up a towel and wiped the bar clean, sweeping his pennies into the trash along with some straw wrappers and cigarette ash that had been left there by him then I gave him the same "I give up" look my mom would use on me occasionally when I was a child, he didn't leave a tip but at least he left embarrassed.

The next year the management for that particular event added 20% gratuity on all purchases "in order to speed up service and avoid confusion" and at the top of the event menu in six languages we put gratuity is going to be included in your bill and on the bill itself the computer automatically added it. The only people that flipped out on me were Europeans and at least I knew that their 20% was already in the pot for the staff/bartenders/me to split after being yelled at in another language. The first year they added the gratuity the complaint/suggestion box that is there for members only and never gets anything put in it because members will go straight to management with problems was filled with illegible and foreign complaints that all had to do with gratuity being added and not a single one looked to be written in proper English. The next year we solved it by putting the suggestion box in the office for the event.

The point of all this is if I can reach just one European and he/she realizes that in America we have to do a little math at the end of every meal out and add just 1/5 of what we payed so the servers can eat and live on a living wage as well then this post will be worth it.