Not no limits; but in seriousness, the USA is a country which evolved from the bottom up with respect to governance. They've always imposed limits on themselves, just like everyone else, but in ways that depend much more on local elected government and positions. A foundational principle is that people institute government to enable themselves to order their own lives. European countries have only weakly, if at all, tried to get away from top-down rule, and mostly failed. Canada is failing. Arguments can be made that people in those countries want that, or something in between, because they do have similar democratic institutions. No question that American dominance in so many spheres has to be more than advantageous circumstances (sparsely occupied continent, cities not rubbled by wars), though. Lots of countries in this hemisphere had the same advantages and failed to prosper as much. Institutional choices matter.
Drilling down, there are a lot of communities where people own a lot of firearms but there is not much firearm violence (or any violence). At least some can "police themselves". Social expectations and enforcement matter.