Really? Why?

In DC, I think it's been pretty successful because lots of gunshots do not result in police calls.

This is an interesting system. I have worked with this technology on large and small scales, and it's a lot less accurate than you'd think. You have no hope of sending a police cruiser to check out a single gunshot based on the outputs of this system. But a single gunshot won't generate a police call in many cities as it is, so no change there. But a gang war? Sure, that will get the phone lines going and also generate many data points to help pinpoint the location using this system. So many factors affect the speed of sound through air, that the problem becomes one of those logarithmic "How many more microphones do you want to install to eke out this tiny bit of accuracy?" kinds of things. I'm not sure it's useful to point to what cities are saying about it, either. The technology itself is a Hard Problem, but I'm also 100% sure many law enforcement bureaucrats will use any excuse to keep money flowing into their budgets, even if the money is earmarked for something that doesn't work (or doesn't work well).

Hm, I'm not so sure. Take this for instance: https://en.wikipedia.org/wiki/Murder_of_Seth_Rich#Shooting_a...

Officers were able to locate and respond within a minute because of a system like this.

Looking into it more it's less clear than I remembered. OPD considered scrapping it in 2014 saying the costs weren't justified and they'd rather have more money for their helicopter. Other cities have said they're not confident in its effectiveness but that doesn't seem to be a large factor here. They ended up keeping it.

https://www.sfgate.com/crime/article/Oakland-cops-aim-to-scr...