"Common sense" is a speculative concept at best, whether you are in America, Europe or anywhere else. And legislation is usually based upon some interest group, no matter how small, pushing for it, not the legislature itself imposing it upon people ad hoc. Yes, Americans may be more fearful and anxious than other cultures, and their extreme sense of "individualism" may have something to do with it (as is exposed in many ways, good and bad). But once you leave large urban areas you find a more relaxed atmosphere when it comes to animals, even where "leash laws" apply.