You have to bear in mind that along with the classics you have mentioned we also produce large quantities of apalling sitcoms which, fortunately for you, never make it to US TV. Personally I love Frazier and many UK critics consider it superior to any sitcoms currently being made in Britain.

Generally speaking we produce two or three classic series every 10 years or so, I suspect the same is true on your side of the great herring pond, but your perception is distorted by the plethora American of garbage you see, and the fact that you only see the best of our stuff.