Many good points made here, but I can tell you, that the European pool scene isn`t that superior as it might seem.
I will go further and say that the US has better requirements to develop strong players than Europe and the simple reason is that the approach to sports in the US is very different than in Europe.
Sports in Europe are organized in clubs, teams etc. which leads to a hard competiton for young talents. A kid in my town can choose between a sh*tload of football (soccer) teams, a record champion hockey team, a ski club which is home to two Olympic gold medalists, 2 volleyball clubs, 3 basketball teams, handball, american football, swimming...not to mention all other activities like dancing, horse riding and so on and so on.
Which leaves me with 4 nice kids, with the high possibility to poke each others eyes out while practicing draw shots.
Not to mention that it is a lot of stress for the parents to bring and take their kids to trainings, tournaments, matches etc. Imagine a family with three kids, all of them active in different sports, at different times and in different places.
In the US many sports are organized in cooperation with schools. High school teams, College teams and even the small ones play for their schools and not a club.
Sports and education in the same institution, Teachers and students, Coaches and teams... and now comes the big if:
IF the US pool community can make their way into schools they will overwhelm the European club and league system in the same way they do it in all big US sports.
As long as US pool gets stuck in this pool hall, gambling, romantic outlaw haze the small European pool scene still has enough capacities to raise players, which are one or two levels above their US counterparts.