The lack clear identification on some has made this description as wide spread as it is. A patch with "Police" doesn't cut it I'm afraid. Same with fatigues, you see people wearing them everyday in Walmart.
I don't disagree with you, with regard to activists being involved, and I don't necessarily have issue with the protection of Federal assets as such, but in a rules based society, blurring the lines of authority can have unintended consequences.