EU environmental protection rules are, generally, rather stricter than those in the US, and Europe does mostly manage to build proper train systems (though not nuclear plants, unless one happens to be France).
It's worth noting that the US has no particular problem building _roads_, visiting from Europe, as a country it seems to be about 50% road. I don't think environmental rules are as big a factor as you think they are in the US's train-y woes.
EDIT: An interesting point of comparison might be Ireland; like the US, Ireland is a wealthy country which can't build infrastructure to save its life. It has pretty much the same environmental rules as other highly-developed European countries, but hyper-local politics and extreme NIMBYism makes doing anything impossible.
There's a proposal at the moment to build a high-speed (ie 300km/h) line from Cork to Dublin to Belfast, but it's more or less tacitly acknowledged that that's the sort of thing you just can't do here, so there is a parallel plan, which may actually happen, to upgrade the existing Cork to Dublin line to fake high speed (ie 200km/h); this is kind of within the realm of the possible in Ireland, in that it doesn't require a new line, so may eventually happen at huge expense. Sound familiar?