This is from an old story, but I've seen this similar story a few times at least: Repo LPR Building Selling Data
Not from that story, but the one I've heard from police officers: These companies read all the plates in an area once a month (targeting areas of higher risk loans), building a database of plate locations, then if you eventually become delinquent in payments, they don't even have to look for you, they know where you park at work every day.
Being a private company, operating on public property, it's out of my base of knowledge if there's anything in US laws that would limit anything they collect, maybe someone here like Mr. Silva would know.