I do not aggree with it at all, if waiters, and hotel cleaners etc don't get paid enough, they should not do the job in the first place, in wich case the wage would have to be increased,
My wife always left a tip for the waitress or waiter in a cafe,
but would never dream of giving a tip to a girl on a checkout till in a supermarket, which in my opinion must be one of the most tip deserving jobs in existence.
It can also put you in an embarasing situation if you are dining out with friends.