So why do waiters in the USA keep pestering me every 5 minutes asking if I need something else? It's part of the culture, and it gets plenty annoying when I'm trying to enjoy a meal but have to stop mid-bite to say "no, thank you" when I'm clearly not in need of anything else.

The feeling I get from those experiences is that I'm being rushed to clear the table, not that the service is great and always there to help me.