Astor, to better answer why there is not more violent action here, it is because people realize there is insurance and any damage done will be fixed free, and put our police to helping them for free as well.
What many may not know is they usually get these mosques built by their members for free, so any insurance payment becomes yet more money for terror supplies, so no, you sure do not want to do violence to their buildings, it has the opposite effect of what you would want. What you want is laws to cause any mosque that terror suspects come from to be forcibly torn down by the state so there would be no rebuilding or insurance payments. Just the way illegal drug labs are removed.
But you know most of the violent sects do not even build anything here in the first place. Most of the bad sects doing this do not have facilities in this country at all, most here in US are indeed peaceful. In Europe however they do have such facilities but they usually do not do terror nearby so as to get a backlash, so far.
What you do need to watch with peaceful ones is where their offerings go, I suspect the purpose of most of the peaceful sects is fund raising for the others. This is why they will stay peaceful, it is useful to their plan. Many so called islamic charities have openly been found to just be terror funding agencies. I am sure that is true of most of the churches as well, even better if they can attract non-violent people to give as well and not know, see?