If they couldn’t use guns, they’d use cars. If they can’t use cars, they’d focus on torture. i.e. instead of trying to kill as many people as possible, just try to make whoever you catch suffer as much as possible before pulling the plug.
Cars are quite a bit slower and a hell of a lot more obvious than a gun. They might switch to that (they have not in other countries) but that would still certainly result in fewer deaths overall. Not sure why they would possibly switch to torture. That one does not seem to have any basis in reality.
You are correct that wealth disparity is one of the big parts of the puzzle. The other big party of the puzzle is how easy it is to get a gun due to how many there are floating around. Things like straw purchases being rampant means that it is pretty easy to obtain an illegal gun. Gun registration would help a bit with that as well as something like requiring a current gun permit to purchase new guns.