Canada, Japan, and Australia have ethnically homogeneous cultures where such acts are still unthinkable to most. They also all have better economies than us. Many factors in play other than access to guns. Still have more problems than Switzerland though, where young people riding trains armed with assault rifles (like, *actual* ones, versus what I can buy here) are extremely common. 

Keep slinging those debunked talking points though, and of course the usual, non-sequitur accusations of "racism" that are the default of lefties with no cogent rebuttal. 👍🏻