Would it be fair to say that the airlines came after GA was established in the USA, and that GA was established after the airlines came in Europe?
Look at Heathrow Airport for example. You see an airport that prohibits private flights, plenty of Class A around it. Schiphol also has plenty of Class A.
London City also prohibits private flights.
People laugh at you and think you must be dreaming when you suggest "But I need to fly my plane into and out of this airport for the purpose of dropping my friend off/attending a business meeting/staying over at a hotel" (etc).
Now compare that with JFK and LAX:
Low landing and handling fees during off-peak times. Surrounded by accessible Class B airspace.
And many people will be wound up and would kick off a storm if the port authority even suggests "it would be nice to kick all these little planes out of my airport".
OTOH, a US trained PPL has probably been trained to fly into big airports, whereas many UK trained PPLs find doing the radio and flying, at the same time, enough of a challenge 
Not saying this is right, or good, or whatever, but if I was running LHR I would think very hard before even looking at this.
Which is a great pity because we have so few GA-accessible H24 airports in the UK. In the south we have just Southend and Cardiff, or Gatwick for a mayday scenario.
Peter, the US has traditionally utilized a mixture of local and imported technical talent and continues to do so to good effect.
Re European innovation in aviation - there has always been a lot of it, the problem is that it so often fails commercially. Hence the imported technical talent in the US.
Innovation in the US is done on experimental category aircraft. Heard of Burt Rutan, Scaled Conposites and the like? Or 8000 RVs flying worldwide, an example of commercial innovation with a solid, reliable, successful product?
Yes, but they have no ICAO CofA, which means they cannot (in general) cross national borders.
They also cannot do overt IFR, outside the USA.
This doesn't matter in the USA, where (at a wild guess) 99.9% of pilots have never left the CONUS, and why should they, but it cripples mission capability everywhere else.
Actually GA is still heavily subsidized in Europe. Most airports receive government support in one way or the other. One of the justifications for this (other than making regions accessible) was to support GA as a prerequisite for the development of new aviation technology. The thinking was that new technology starts in GA and then eventually moves up to airliners. Also private pilots used to become airline pilots.
That no longer appears to be the case. 18 year olds start an ATP program without having flown a small aircraft. After 50h in a C152, 15h in a Seneca, all they see until they retire are Boeings and Airbuses. Companies like EADS don't care about GA and openly tell the politicians that it is of no importance to their business or recruiting. They are large enough to develop everything from scratch.
Until a few years ago Soccata was owned by EADS. That was after they stopped making piston planes but even something like a TBM850 is of no interest to Airbus.
One can't talk of Europe as one place, not in this context and neither in many others. G/A is not too bad off in France, where many aerodromes are operated by some local authority just like in the US. Countries like Holland and the UK tried to make a/d operation commercial ventures, with obvious deplorable results for recreational flying, but not too bad for small corporate operations in singles or twins.
Specifically European problems are the variety of languages - try English R/T in Spain, or in Russia! - and the variety in local regulations. Add to that the very intense airliner traffic making for very congested airspace, even as low as FL60 or so. Where those problems are not too bad (Baltics, some Balkan countries, Portugal...) conditions can be considered reasonable. But petrol is more expensive over here anyway, be it for a plane or a car or a lawn mower.
As for WW2, we should not forget its large effort of aerodrome creation, many current aerodromes stem from that era. This includes both major airports like EBBR Brussels and green fields like EBGB Grimbergen.
I think it has plenty to do with the politics of envy. In Europe if you park a Rolls Royce in the street someone will probably run a screwdriver down the side of it saying " I'll teach the rich b****rd a lesson". In the USA passers by would say "wow, thats a great car I'm gonna get one of those when I make it"
a lot of truth in that
The lack of Experimental Category in Europe is definitely an issue. US aviation went to innovation by this route en mass 30-40 years ago. Its the US parallel to the microlight movement although with wider range including any kind of aircraft and IFR equipment and operations. Apart from training, US GA is now centered on rebuilding old aircraft and designing and building new Experimentals, at lower cost than buying factory built aircraft (including European-style micro lights).
Again, "Europe" does not exist in this context. The F-Pxxx registry is as doable as any for experimentals. OTOH homebuilding for the Belgian OO-[0-9][0-9[0-9] is as elusive as Utopia. To name just two samples.
Here in the USA we have a very good interstate road system but our speed limits are low, certainly in comparison to Germany. We don't have an equivalent passenger train transportation system that is available in Europe. Airline travel is very burdensome, particularly since 9/11 and everything is Hub and Spoke, with full airplanes. As of 2011, there are some 547 airports served by the airlines and 19,784 total airports, of which 5172 are public use. A very few number of airports (I would be surprised if they number 50 in the entire country) charge a landing fee, that is how they keep GA out. Overnight parking is typically $10 a night with one night waived if fuel is purchased. 100LL runs between $5 and $7 a gallon and the current price is $5.65 USD a gallon at my home airport (if I did my math right that is .94 £ per Liter). At the big airports the FBO's charge a handling fee that is typically about $25. The fuel taxes which are included in the fuel price are the only contribution we have to pay for receiving ATC or FSS services. There are no overflight fees and no flightplan fees. We don't need to have a radio operators license and our pilot certificates do not expire. We require an flight review every two years that is administered by a CFI, you have to pass it but you can't fail it. Instrument privileges require 6 approaches, a hold, navigating by electronic means within a six month period. We can have a safety pilot sit in the right seat and reestablish currency if it has lapsed as long as the lapse hasn't extended another 6 months since we were last current. If it does, we have to fly with a CFII who conducts an Instrument Proficiency Check and we are back in business. We aren't mandated to have a 406 ELT or a mode S transponder. By 2020 we are mandated to have ADS-B, but we will get free traffic and weather in the cockpit as a sweetener.
BTW, we are good at complaining about the high cost of aviation. If we had to deal with typical costs outside of the USA, our numbers would be severely reduced.
