The problem here is untrained, unrestricted and unsupervised access to guns. You’re right that we don’t want psychos owning guns in general, not just 13 year olds. Look up the steps to getting a gun in Canada, you just need to take a safety course and pass some background checks. That’s to add assurance that gun owners know what they’re doing, and aren’t psychos. In this case the kid had unrestricted access to a gun without supervision, because his parents were either untrained to understand proper storage, or irresponsible. Training is a big part of keeping guns out of the hands of people who have not been verified to be responsible to own a gun unsupervised, like this kid.