Currently there is technology called ALPR, automated license plate readers which automatically read your license plate. There is strict limitations on the use of them and access to the data. For instance at the ATL airport your license is read when enter the parking lot and a vehicle with ALPR equipment drives through the lots daily to record the parked cars and references the data with geo-location. Several times a day, there are travelers who forget where they parked their car and they have to go to the Airport police station who are the only people allowed to access the data. After verifying ownership they take you to your mis-placed car. Equally so, there are ALPR unit mounted on patrol cars (those two boxes on the truck lid) which continuously scan plates for stolen vehicles or wanted individuals. The use of and the storage of the data varies by state but suffice to say, the data cannot be stored very long if at all and its use limited by law. My car wash uses ALPR to verify my membership, but it cannot store, when or the fact that I was even there. It can only "verify" I am on the membership list.
I find it interesting that the general public and the state and Federal authorities have a lot of "heartburn" over ALPR data, but have zero problem depositing ADS-B data willy nilly to anyone. Yeah, the crazy can wait outside the Montana for John Lennon but the fact is John Lennon could have used the secure entrance but chose to meet 'his public". I think we all have a right to be "modestly secure" in our comings and goings. The belching out of this ADS-B data would not be tolerated by the average citizen just as ALPR data is not. Heck we even require dispersal of firearms personally identifiable sales data and its destruction from central databases after 90 days. Why? Because they have better lobbyists than we do in aviation.
Of course I have an Alexa in my house, but that is my choice.