I think it depends a lot on authorial intent. I think portraying guns in media is fine, it's how they are portrayed or used that makes a lot of the difference. For instance, Japan doesn't have a lot of shoot outs but they have a huge amount of guns in their children's media (notably often regarded as under Parental Guidance). The guns are usually only portrayed in certain contexts.
-as weapons of war and violence, which is unpleasant
-as absurdist power fantasies (because untrained people are unlikely to hold a gun in public), usually only used against monsters and zombies.
-as a hobby for people under very strict rules (strict shooting range rules)
-as tools for the police/military to threaten criminals (though not expecting to take the shot)
-as something really bad people use to do really bad things, because they're straight up mobsters or cultists
The same goes for most of Europe.
In an American context, this stops working mostly due to the common nature of guns. An assault rifle is no longer equivalent to a murderunicorn, it's something you could run into at any time.
Nobody should force the creators to make a decision one way or the other, but it's completely understandable if they just don't feel like portraying guns because they can't think of a way to make it fun and tasteful.
As for weapon rules in comics, I think it varies depending on genre. Guns are a tool of either sports (sharpshooting, paintball...), violence or intimidation. As long as sports are portrayed with the right care, and violence and intimidation are portrayed in either an undesirable or completely absurd light, then I'm fine with it.