> enjoy visiting Eastern Europe(and Europe in general) where a party can sit at a table at 7pm, dine, drink, talk, and relax and remain there until close at 1am if they want

Would note that this is common at high-end restaurants in America. (Unless they sear at 10 or 11PM, in which case they may want another turn of tables.)

It depends on the restaurant. If there is a line of patrons to be seated they will definitely nudge you toward conclusion. Even if they are not busy the more customers a waiter churns through the more they earn. I find tips deceptive. One is not evaluating service quality. It’s just letting them advertise prices at 75% of actual cost before 20% de facto mandatory tip and 10% sales tax.

Where? NYC? The densest cities in the country? If you get outside the metropolises it's not like that at all. That's just a reflection of demand and population density.