ICE goons can shoot people because in America, law enforcement officers shooting citizens is thoroughly normalized. It's normalized because law enforcement officers getting shot is thoroughly normalized. It's normalized because the nation decided every village idiot can have a gun and the government can do nothing about it.
These devices are over a century old: the cat's out of the bag, manufacturing technology has only gotten better and easier.
You so much as walk around with your gun in the streets of Seoul, and you will very quickly find out that the government can, in fact, do something about it, it will do something about it, the general public will side with the government against you, and there's nothing you can do about it.
Gun ownership is a social construct. Where guns are banned, even criminals can't afford one, because there's no place to get these guns in the first place. Those who think they can outsmart the government will quickly find that guns out in the wild is considered a matter of national security and handled accordingly.
Only if you're caught - which requires more than magic. Shinzo Abe would disagree.