It’s a meme about how every video from Brazil is some criminal with a gun interacting with someone else in brazil who surprise! happens to be a police officer in plain clothes with a gun of their own. This may surprise you, but I’m aware that not “everyone in Brazil” (which would include grandmothers and toddlers and shit) is actually an off duty cop.
So yes. “They don’t carry weapons” because “they aren’t legally allowed to carry the effective ones.”
Legal gun ownership boomed with it “becoming legal.” This indicates that the reason those people weren’t is because it “wasn’t legal.” Those people want to carry, they just “follow the laws” unlike all those people who actually do carry guns in Brazil that we’re ignoring because they’re criminals.