I don't think I'd call it a controversy exactly. There are places where the signs make sense (ex court buildings) and then there are places where they are purely performative. When a school in the ghetto that suffers gang related violence prominently posts such signs they rightfully get made fun of. Meanwhile most schools (at least where I grew up) either don't bother to post such signs or only post a subdued "all weapons illegal" near the entrance (that includes even pocket knives BTW it's not just a gun thing).

Another great one is "drug free zone" seen plastered all over a seedy highschool. Drugs are blanket illegal everywhere here. The US has made an art form out of persecuting drug users. We've peddled our "war on drugs" globally. What could possibly be the point of posting such a sign?