Liberal Gun Owners

There's plenty of ways that can happen. Maybe they are diligent about keeping their guns locked up when not in use, and don't think they'll need to consider telling the kid to not touch guns. Maybe there's a communication issue between the parents, and they each assume the other is giving the kid(s) instructions like that and don't want to repeat.

Not only that, telling the kid "don't touch guns" when they're 3 isn't going to work all of the time, but it will work some of the time. There's no reason to not tell this to kids at school since it costs nothing and can help keep them safe.

And with the direction you're going, I'm going to head this off: having a licensing process requires a registry. I don't trust the current administration to not abuse that kind of information. Plus, there's a decent chance of a leak, resulting in criminals learning which houses have guns in them that they can break in and steal.