I mean that if someone threatened me with a weapon for whatever reason, I drew my firearm in preparation to defend myself because I had no other choice, she the attacker decided to cut and run instead of risking it, why would I call the cops and invite all the hassle that dealing with American cops brings?

There's no suspect, there's little evidence, no shots fired, presumably no harm to me, and my choices are to call 911, try to convince them that something happened and to send cops, spend hours going over details, and end up nowhere; or I could simply collect my wits and get the hell out of there.

Hell, after I was attacked and nearly killed, the cops and the DA both said to me face that since there were no witnesses, and the area was rough, there was basically fuck-all they could do and zero chance they'd ever find the guy, and my home town is relatively small.

Studies and data from the FBI generally show, too, that many encounters of various kinds like I described above go unreported because people don't want to deal with the cops. More so if they're a minority.

So tell me again, how do you propose to track incidents where someone draws a gun in self defense, but things never get to a point where shots are fired and police aren't involved?