I agree it's intrusive. I have to put up with 4 inspections a year now, in subsidized senior housing. But, they're quick, and the reason they are required, is mainly to make sure I have decent housing. They just make sure the fire alarm works, smoke detectors work, heaters, etc.
If they got out a camera, I'd shoo them out the door. I would not allow it.
When I was a manager, we did really quick inspections every 6 months, checked the smoke detectors, quick check to see if there are leaks under sinks, mold in shower, if a/c unit was leaking inside, asked tenant if there were any issues, and off to the next one. Not intrusive.
Again, our reason for inspecting was to make sure things were working - not to spy on the tenants.
I think you have to think about what kind of tenant would put up with that kind of invasion, and what kind would not. You're only going to keep the kind that would be okay with that. And I don't think that would be a good thing.
Some landlords and property managers forget that tenants are people, and that when they pay you rent, they are purchasing the right to be able to live in that unit as if it was their home. If you treat your tenants like naughty, secretive peons, the only long-term tenants you will have will be naughty, secretive peons. Like a self-fulfilling prophesy
The fact that it gave you a hinky feeling goes to show that it's not something you'd be comfortable with, so that's a good indicator that your tenants wouldn't love it either.
You just can't treat people badly, and then expect them to be a long-term ATM machine that spits out rent every month forever.
But, of course, your PM probably makes money every time the place turns over, so they don't care if they are irritating the tenants and having to get a new tenant every year, because none of the tenants want to stay after their lease is up.