You can't even buy ammo from a vending machine in GTA. You still need to go to a gun store for that in the game. You can tell Rockstar have been slacking when real life gets ahead of their satirical game.
In Cyberpunk 2077, you can buy a gun from some vending machines. It is made out of plastic and cannot be reloaded, but it's a real gun. In this case, I'd say reality outdid the sarcasm.
Honestly just start a rumor that they are put in place by the FBI to get biometrics of local gun users.....they will be out of business or vandalized by next week.
Honestly, the only people using these will be the rich wannabe-redneck republicans who like to post their gun collections on instagram. It's an opportunity to virtue signal your gun fetish and nothing else.
Vending machines are great for when you need a small amount of something on the spur of the moment--but kinda worthless for something like bullets (presumably, if you're planning ahead to have a gun on you, you would also have thought to stuff a few rounds in your pocket at least) When they start selling actual guns, then I'll be worried.