Mass shootings/stabbings/using trucks to run people over/bombings do happen in the European countries and all other countries you can think of, for various reasons, as well as in the USA. For the USA having the most amount of guns per capita it doesn't rank the highest in gun violence, in fact some European countries rank higher than USA.
One of the problems with the wording of mass shooting is that it lumps in lots of things that are un-related. If I remember correctly, anyone in a gang style drive by shooting where 3 or more people were shot is counted as a mass shooting, or any event where 3 people are shot(doesn't matter which side). I haven't specifically separated all of that out, but it would need to be separated from school shootings by teens. Then things like workplace disputes/family disputes where guns were used would need to be separated, as well as people breaking into a home and shooting up the family or whatever.
So there a lot of moving parts to separate and look at. For example, the people in the gang style drive by shooting who got shot were likely a rival gang being shot at by another gang. There wouldn't be a mental illness involved in that scenario as it usually is the case for school shootings. By grouping everything together in a mass shooting it makes the problem seem bigger than it is. Gangs operate illegally so they would need to be removed from the equation on any gun control factors for instance.
Then there is also all of the good guns do nobody ever really talks about. Ijust recently made a post about how 200,000 women per year use a gun in self defense against sexual abuse(brandishing the weapon/threatening to use it/actually using it). On a yearly basis something like 315,000 women and men are sexually abused each year, while only 1/3 of the USApopulation has a weapon. Statistically we know that it isn't linear, and that if 1/2 of USAowned weapons that the number of sexual abuse might be cut down by a huge percentage. Also, per year there is roughly 1.5 million to 2.5 million legal uses of a gun for self defense(1.5 million from the Bill Clinton study during his Presidency). With the super majority never firing a shot at anyone.
Guns overall do more good than harm by a factor ot 70x to 80x and the number is 47x if you look at the study done by Bill Clinton's administration.
Now, this isn't to advocate that everyone should have a weapon either. Certainly mental illness funding has been cut for decades. People used to be involuntarilty put into asylums through the mid 1900s and now they roam the street. The majority of homeless people are actually mentally ill or have mental cognitive issues. It is a very sad state to see how things are like that, I would rather us not bomb these middle eastern countres and instead use that money here on our own people for helping and establishing places for them to live/food/shelter/mental health help/etc.
But currently we don't have that and a lot of mentally ill people/people on medications that cause psychosis are killing people using weapons. I don't like it at all.
The most practical thing I can see happening, is that we do have police officers in schools/churches/places with lots of people. We have them in malls and amusement parks and stuff like that, why not all places. All throughout history guards would patrol the marketplace/political buildings/common areas/schools/churches and were on the look out for bad people/thieves/murderes/whatever. I don't understand why society thinks we don't need these protections, but at the same time when something is happening we all dial 911 and have to wait 20 to 30 minutes for someone to show up and help.
We could do that +have more mental health funding and it would really reduce things like this from happening.