it's not about filming in public. it's about systematic data collection by law enforcement, using private infrastructure present by its nature in public. that's why the Carpenter decision is relevant.
The Carpenter decision was about the US government compelling mobile data providers to hand over private use information. It's really not relevant to flock. That's why the 9th Circuit decided that automated license plate readers don't need a warrant. A cop and stand at an intersection and write down license plate numbers without a warrant. A device can do the same.