I've seen numerous people on the forum say they feel like they get more respect when they clearly have a camera, a few videos where someone (sometimes a cop) was clearly getting belligerent then they realized they were on camera and backed off and acted more civilized, and police body cameras seem to reduce both cop abuse but also suspects trying to pull something.

I don't have a quick link to it, but someone had a video riding their recumbent where a guy in a pickup truck passes, stops in front them, gets out and comes back, and you're not sure if he's going to try to fight him or what, but the rider turns his camera to make it obvious the guy is being recorded, and the guy turns and get back in his truck.

I definitely think it's a safety device.