Cops can’t be everywhere. Nobody is installing bollards around markets or on bridges, generally speaking.
There is always a potential victim base, whenever you’re outside your home, regardless of whether you use a firearm or vehicle.
It really is that easy. Besides, most “mass shootings” result in 1 or zero people killed:
Mass Shootings | Gun Violence Archive
Gun Violence Archive (GVA) is a not for profit corporation formed in 2013 to provide free online public access to accurate information about gun-related violence in the United States. GVA will collect and check for accuracy, comprehensive information...
If someone wants to commit murder it’s practically impossible to stop them. You can make toxic gas out of things in a grocery store. People need to cut food. Those things are no where near as easy to kill people with. Gun you point and shoot. Knife you need to have a certain level of physical competency, be in arms reach and hope they can’t defend themselves. Last I checked cars don’t work in hallways of school corridors.
Not in corridors, no. But there’d be no problem driving onto a school oval or around a bigger open campus, etc.
Knives don’t need real competency. Point goes in person, repeat ad nauseum. People die from single stabs as well as single gunshots, it all depends on where you hit.
Cars work great in the middle of Melbourne, though. And in Nice, London Bridge, etc.