A number of states already have laws preventing individuals from setting up ALPR. I can't image state or government officials that don't lready have those restrictions in place would allow the public to set up tracking of their movements for very long if someone did try to set up something crowd-sourced or easily searchable.

e.g.:

Arkansas: https://law.justia.com/codes/arkansas/title-12/subtitle-2/ch... > Except as provided in subsection (b) of this section, it is unlawful for an individual, partnership, corporation, association, or the State of Arkansas, its agencies, and political subdivisions to use an automatic license plate reader system.

Maine: https://legislature.maine.gov/statutes/29-A/title29-Asec2117... > Except as otherwise provided in subsection 3, a person may not use an automated license plate recognition system.

ADSB stuff falls into the much broader legal concept in the US that airwaves are public and if you can receive it and aren’t cracking encryption then it’s fair game to listen to. Many countries have a far more restrictive view of radio traffic, and encryption in ADSB isn’t likely to happen anytime soon if ever.