I mean I only have a handful of trips and experiences to go off of, but I don't recall seeing nearly as many waiters in European restaurants as I do in the US. I recall outdoor seating areas in Paris with 10+ tables having 1 waiter. Here there would be multiple waiters. Since we don't pay waiters a high salary, and they are mostly tips, it is easier to hire more per shift.
I usually see them working (although a cigarette break has happened), not standing around ignoring customers. I get why the overall meal takes longer, but the waiters don't provide less service (or make it harder to interact with the customer) in order to enhance your dining experience. I don't think they want me impatiently waiting for another drink at Aperitivo, yet it happens. I assume it is because they are busy, and the incremental tip from another beer isn't as critical.
We have high end steak houses in NYC where your meal takes hours, on purpose for the experience...but you also don't have to refill your own glass of wine. The waiter sees you are almost out of wine and automatically comes over to pour your glass. Why? Great service + increasing the # of bottles of wine ordered = Potential of a larger Tip.