They are covering all the surveillance cameras because they are doing something they don't want you to see

In the last few months, or longer, I have noticed surveillance cameras all over the place covered by a small black plastic plastic bag. They are collecting all this data, so it can't be that they are too expensive to keep, so what is the reason behind all the surveillance cameras being covered? <br><br>We all know they can do the scary things they do when no one is watching. So why are they covering all the surveillance cameras, It would make more sense if they were putting more up, the more the better, right?