There are plenty of places, such as western European countries and Japan, that have strong safety regulations and still manage to complete large-scale infrastructure projects quickly.

Another way to look at this is to ask why the United States seems incapable of even maintaining existing projects. For example, look at the current state of the New York City subway.

I suspect slowness in building new infrastructure, and poor maintenance of existing infrastructure, have the same root cause: lack of political will.

American voters don't expect their governments to be good at this kind of thing. European voters would vote politicians out of office if their transit systems got as bad as the NY subway has become. It would be seen as a failure to execute one of the basic duties of government.