It’s weird because Switzerland is one of the most armed countries in Europe, as in they have firearms but barely any shootings of any kind (so you don’t often hear news equivalent to a guy shooting students in a classroom or killing people at a shopping mall over there). Part of it has to do with the draft (most people who purchase firearms have a form of training, as they learnt how to properly handle them during military service).
I can only comment about what goes on in the US. In many states you cannot just carry the guns wherever you want. In states that allow you to carry a gun that’s concealed, you will need a special permit. Some states don’t require this though. If you are carrying in the open, some states allow this, but many don’t. There are also rules about where you can take the gun. For example, many states do not allow you to bring it on school property.
In California you very very rarely see anyone with a gun. In some red states it’s pretty common.
The issue is easy access to guns with ammo and the culture behind them.