plenty weather over there, infact I've encountered far more severe weather flying in the States than anywhere else in Europe
During hours building?
The T/O x-wind limit is circa 12kts for a Cessna 152 - so I'm not quite sure what your point is and what you are comparing.
Its quite simple. People go to states because of the allegedly cheaper cost of hour building. This comes from lower fuel cost, charges blah blah.
If you go an airfield with moderate traffic (hence being situated in an airspace with moderate traffic) then obviously the airfield charges will cost more compared to some dirt strip in the middle of Nevada. So straight away you have lost the whole cost difference that you originally went for.
Also, the other attraction of the states is the weather where you can pretty much guarantee blue skies for weeks on end unlike in England. You could easily build a 100 hours in 5 weeks (if you flew 4 hours per day). You won't book your ticket for Florida in the middle of hurricane season would you?
So in summary the attraction is weather and costs therefore weather will be nil, and air traffic will be next to nothing.