a cop can stand there and listen to what you say, even record it if they want. It's a public place.
The difference is that it used to take some effort to track what one person was saying in those public places. With technology making it nearly free, we're all facing every public moment of our entire lives being stored forever in some law enforcement database.
I'm fine with the local police getting copies of business' surveillance tapes, interviewing people, and checking telco logs to piece together my actions, AFTER there has been some credible accusation that I've committed a felony. But doing it all day, every day, in minute detail, storing it forever, etc., is massively crossing a line into police-state territory.
Your argument is akin to peeping toms protesting their innocence because you don't have an expectation of privacy when absolutely anybody could have been standing on a ladder, with a high-powered scope, taking pictures through the crack between the curtains, so it's all your fault, not theirs.