Its by design. By using a third party, they can get around the 4th amendment.

Using a third-party to bypass legal restrictions should in and of itself be considered willful and knowledgeable intent to violate the Constitution under color of law, regardless of the specific actions taken

I'm not convinced they can always get around it... I think they could challenge their arrest in court on Fourth Amendment grounds and have a chance at winning:

https://epic.org/vehicle-fingerprinting-through-pervasive-ca...

>In the 2018 case Carpenter v. United States, the Supreme Court affirmed that individuals have a reasonable expectation of privacy in their long term movements (even in public spaces) and, because of that expectation, queries into long term location tracking data constitute a Fourth Amendment search that requires a warrant.

I suppose they would also have to argue that they are not the actual target of the warrant.

How are they not an 'agent of the state' and how does the 4th not apply? If the government asked for the scan/info on the vehicle, they are acting on behalf of the government?

https://www.fletc.gov/audio/definition-government-agent-unde...