They take everything to-go.
Perhaps it has something to do with the American ideal to not waste a single minute, but Americans are always on the go. They eat while they walk and they drink their coffee from paper cups while on their way somewhere. In Europe, coffee in all its forms would be consumed while sitting at a café or standing up at the bar—never while on the go.
The dining aspect of many cultures is something to be respected and focused on, while the American focus is on getting as much done and wasting as little time as possible. Because of this, eating and drinking are often seen as obstacles to overcome and “fast food” is the way to go.
And speaking of…