The thing to remember is that most folks -- other than some lawyers -- don't get what they believe about the law by looking at, well, laws or court cases, most of the time. I know that at least some cops believe this "Peace Officers Bill of Rights" nonsense because that's what they learned in cop school, from their instructors.

To quote one instructor, "and if you don't think it really works that way, just try taking a picture of a cop when he doesn't want you to."

[ETA: There were witnesses, so I smiled and asked, "Great. Most cops do own their own houses, right?"]

Massachusetts trial court decision rejecting Wiretapping / Disturbing the Peace Charges against man who recorded a police arrest is at
http://volokh.com/files/glik.pdf