Photo Radar Bell Rd and 21st Ave

I'm sure everyone knows where these radar machines are and the posted limit. I live west of the 17 on Bell and pass by 3x times a week. The have never received any citations from that camera.

Not why I posted this.

However, 9/10 times I pass by at EXACTLY 45mph (posted speed) get flashed by the forward flash bulb. I've noticed it's only in groups of cars, as I've never been flashed if I am traveling solo on Bell.

My vehicle speed is accurate, confirmed by gps. Posted limit is 45 before and after. And that seems to be the only PHX pd camera that does it.

What gives?