The overwhelming majority of people are probably ok with recording plates at the border. If it's confined to the border it's not really any different than the customs agent jotting down your license plate. It's also not really "tracking", it's just a record created at that single point. It's the whole network that makes it "tracking"

It's the record keeping everywhere else and tracking that that enables that's not ok.

Jotting down on paper is not the same as aggregated and uploaded to an open ftp server.

I honestly support license plate readers on most roads, if they were used for average speed measurements and in conjunction with automated ticketing of people speeding.