I don't understand why the police even care if they are being recorded. They are well training and should know the boundaries in which they need to operate, so

I don't understand why the police even care if they are being recorded. They are well training and should know the boundaries in which they need to operate, so someone recording them shouldn't be a big deal. Heck, a lot of times they record themselves (dash cams). Disclosure: I have two brothers that are police officers