You seem to be under the impression that other countries experience even a fraction of the violence Americans experience from guns.

We don't. What's happening in America with the gun violence is uniquely horrifying.

You're gonna have to explain your point better. No one said mental illness doesn't exist. Your comment has nothing to do with the definition of mass shootings. No one defines mass shooting as "a mentally ill person who shoots people." It's pretty much given that a mass shooter is mentally ill. The point of contention is what does "mass" mean.