One difference is that in Europe wait staff do not rely on tips.

I think it’s fine to enjoy a leisurely meal, particularly when no other customers are clamoring for a table. I’ve done that many a time. But when I do, I always leave a commensurately large tip because I know that servers in America need them to survive.

Because the servers need the tips, from their POV, they’ll earn less if the tables aren’t being churned. Of course, when the place is pretty empty that’s a moot point.