This is a direct consequence of how food service employees are paid in the U.S. They have an income of next to nothing and depend on tips. Tips do not play such a large part in (most? all?) of Europe and are smaller than in the U.S., so customers that stay longer mean less work without too much pay reduction. At least that is my pet theory. I only visit the U.S. every couple of years and this year I noticed that the "standard" tip crept up to 15%-20% instead of the 10%-15% that I remember. Seems that employers are paying food service workers even less of a wage than before.