Why is exploration of Shale gas in Europe so much slower than in U.S.?

When talking to operators like Talisman or Chevron, a number of them commented on how they were always asked when the shale revolution will take off in Europe. If the U.S. can do it so rapidly, then why can’t Europe? Is there a danger Europe can be left behind?

I’m starting to compile a list of what is different between Europe and the American Shale Boom. Below are what I believe to be the top inhibitors in Europe:

1) Property Rights

As the Economist sums up in an  excellent article:  ‘In America individuals generally own the minerals under their property. Since a gas strike will make them rich, they will generally be enthusiastic about extracting the stuff. In Europe mineral rights mostly belong to the state.’

2) The threat of environmental protest

3) Density of population

4) Lack of proper regulation of pipelines

5) Lack of government subsidies

6) Lack of drill-rigs

Any one want to add a few?