> making the average investment smaller and the average investor more conservative and wary

X Million dollars are worth the same regardless of the owner (US vs EU). On the other hand a smaller average investment size should make the deals so much more lucrative and a turf worth defending.

Edit : on second thoughts it may have more to do with the cultural issues(as you pointed it out) combined with the regulatory boundaries e.g. amazon.de can't deliver half the things to Switzerland.