Here are 2 facts -
#1 There is a mass shooting in the US almost every day
#2 There is around 1 firearm for everyone in the US
After Scotland had a mass shooting in 1987, London instituted strict gun control laws. So did Oz after a 1996 shooting. But the US has repeatedly faced the same calculus and determined that relatively unregulated gun ownership is worth the cost to society. That choice, more than any statistic or regulation, is what most sets the US apart.
What makes me sad is that gun control debate in the US seems to be over, the consensus being that all these killings, be they in a school, theatre or anywhere else, are bearable in the name of freedom.
I can honestly say, with no offence intended to my American friends here, that I never would wish to live in the US. There are some culturally bridges that can't be crossed. I'm not aware that Jesus or Buddha went about their business armed with anything but a heart full of unconditional love.