Why do you think the government couldn’t collect this information themselves? ALPRs are legal, cameras covering a public roadway are legal, and the 4th amendment doesn’t extend to driving on a public roadway.
Of course they can and of course they do. It gets much more complicated when you consider that each state has different laws about records sharing.
And, lol, yes the 4th amendment extends to driving on a public roadway... roads aren't international waters. Probable cause and such are still important. I recognize what you're saying but -- details matter, dammit.
Could the government set up 80,000 cameras to spy on everyone? No, they are not aloud to create dragnets or conduct mass surveillance. They need warrants.
Thats the loophole that flock capitalized on.