Because when you are in a public place you have no right to the expectation of privacy. If you are walking and talking down the sidewalk in town other people are able to hear your side of the conversation. Depending on if your state and the state the other party is in are two or one party states it is a moot point.

it's not really the legal problem.

It is a legal problem. The Second Amendment is perfectly clear — keeping and bearing arms is a right. Any and all laws imposing licensing requirements turn that right (which can only be taken away by the Judiciary) into a privilege (to be granted and withdrawn by the Executive), are just that: Unconstitutional.

the culture of guns in the usa is fucking retarded

That may or may not be so. I tend to like it, however.