The places with the highest rates of gun violence all have bans on guns.
What total nonsense. The country with the highest rate of gun deaths in the world is - according to wikipedia - Honduras. Up until 2007, carrying guns, concealed or otherwise, was completely legal in this country. Today it is still legal to purchase and own firearms. So, no ban.
Some others on the list have bans, but it's clear that there is no correlation between ownership rates, legal status, and death rates. So, banning guns doesn't stop people getting killed, and widespread gun ownership doesn't either. You can point to counterexamples in both cases. America has the highest rate of gun ownership, and while it doesn't lead the world in gun-related deaths (it's only at number thirteen, mainly behind fairly lawless countries I'd argue, but that's a tough call), it's certainly up there.
America does however lead the world in mass shootings - and that list doesn't even include school massacres (How is that even a thing? It's a serious question). Mass shootings are something different to regular gun violence. We're not talking about armed robberies, or criminals shooting each other down in the street. We are talking about crazy people. I don't think there's any reason to believe that America is home to more crazy people than anywhere else - I've been there plenty of times and Americans as a rule are polite, hospitable, pleasant and reasonable. It's a nice place.
So why do crazy people in America have such easy access to deadly weapons?