I think it goes beyond that — America is a society that relishes violence against others. In the past one hundred years or so it has been in an almost continual state of war. Wars against far away countries that pose no threat to America. Mostly poor third world countries. Murdering your own citizens is but an extension of this thirst for blood.
And for the record, Australia has never banned guns. Following the Port Arthur massacre in 1996 the federal government legislated stronger licencing and ownership rules. Any citizen may own a wide variety of guns, including handguns. Possession of semi-automatic weapons is also possible in certain circumstances, such as feral animal eradication. But weapons must be stored in a locked steel case, secured to the wall or floor of the dwelling. And the police conduct background checks of the applicant to to preclude those with a background of violent offences or mental instability. Possession of fully automatic rifles is restricted to defence force and police.