You make some good points, though I still disagree. It's against the rules for criminal RPers to use voice chat, and imo it should be, but it should also be the same for LEO RPers.
Yes, the leaders of LEO factions say that they heavily moderate VOIP, but all I've seen is the opposite in my several years of playing, so I'm sure you can understand my scepticism.
I've observed LEO RPers actively calling for backup while literally standing in the middle of the street shooting at somebody, which shouldn't be considered cool in my opinion, I was even in a situation some time ago where an officer that was shot down continued calling for backup even after he was death screened, the only reason I found out that he was doing so was because he recorded it and reported me for whatever reason, which is why I'm sceptical when I'm told that VOIP is heavily moderated. It's easy to say that it's heavily moderated, but it's hard to really prove that.
Police aren't supermen, even if they have 'gadgets' at their disposal. If you're actively being fired at by multiple thugs, you're likely gonna be in a state of panic, I doubt you'd be able to reach for your radio and calmly broadcast your location all while shooting back and reversing your car in the process, your aim is gonna be staying alive and not catching a bullet to the forehead.