I think it hugely depends on which of the cultures you grew up in. I grew up in an interrupting culture family - interrupting was just the norm, nobody considered it rude. My wife grew up in a wait culture family. If I interrupt her she can get really mad. Over the years I've had to learn to use the wait-method when talking to her and it's made me more mindful of the two different cultures. I try to do more waiting than interrupting anymore since I now realize there's a large percentage of the population that considers interrupting to be rude.
There's also another thing that the waiters can consider an interruption, but I guess I never considered an interruption - saying something in agreement with the speaker as sort of an affirmation of what they're saying. My wife considers that an interruption, I consider it just participating in the conversation.