Couldn't governments just remotely disable phones nearby to prevent evidence of police brutality from being recorded?

I mean, I see "leaked" videos of protests in authoritarian countries like China and just wonder why they dont just like make a backdoor that disables videos from being recorded. Or use some sort of 0-day exploit that installs malware on their phones and disable cameras.

I mean, I can't be the only one that thought of it, right? Surely someone in the government would've thought of it.

Wonder why such tactic isn't being used.