It's just chalk and cheese. I have said before the U.S relies on visual approaches and separation but this is rare in Europe, where the radar controller is almost always responsible for separation. Radar CONTROL service in the U.K. The radar controller achieves this in a number of ways - if the runway in use is also being used for departures they will liaise tower to achieve spacing. If not it is usually achieved by speed control - maintain 160 knots between nine and five miles- for example.
I can't work out whether the U S just likes it the way it is, the traffic is too heavy to do things the way they are done in Europe or what. The advent of Live ATC enables me to listen to US controllers - To my U K ear it often sounds like things are not really controlled at all. There are advantages - GA traffic would never be able to access all the airspace here it can in the U S here for example.