The Driver's Privacy Protection Act of 1994 (DPPA) restricts who has access to DMV databases - and as you note, these DMV databases are not public record.
However, anyone can pay a licensed private investigator to obtain this information - as long as they assert that the request is for a 'DPPA Permissable Purpose'.
Below is copied from a licensed PI firm named Docusearch
Pursuant to the Driver’s Privacy Protection Act of 1994 (DPPA), you may only access vehicle registration information for any of the following permitted uses:
1) Litigation/Pre-litigation: For use in connection with any civil, criminal, administrative, or arbitral proceeding in any federal, state, or local court or agency or before any self-regulatory body, including the service of process, investigation in anticipation of litigation, and the execution or enforcement of judgments and orders, or pursuant to an order of a federal, state, or local court.
2) Debt Recovery/Fraud Investigation: For use in the normal course of business by a legitimate business or its agents, employees, or contractors, but only—
(a) to verify the accuracy of personal information submitted by the individual to the business or its agents, employees, or contractors; and
(b) if such information as so submitted is not correct or is no longer correct, to obtain the correct information, but only for the purposes of preventing fraud by, pursuing legal remedies against, or recovering on a debt or security interest against, the individual.
3) Government Agency: Use by a government agency, but only in carrying out its functions.
4) On Government Behalf: Use by any person acting on behalf of a government or law enforcement agency, but only in carrying out the agency’s functions.
5) Insurer/Claims Investigation: Use by an insurer or insured in connection with insurance claims, claims investigation, or anti-fraud activities.
6) Motor Vehicle Safety: In connection with motor vehicle safety or theft, or driver safety (except by or for a motor vehicle manufacturer).
7) Employment: Use by an employer or its agents or insurer to obtain or verify information relating to a holder of a commercial driver’s license that is required under Chapter 313 of Title 49 of the United States Code.
8) Towing/Impounded Vehicle: For use in providing notice to the owners of towed or impounded vehicles.
9) Private Investigator: Use by a licensed private investigative agency or licensed security service for a purpose permitted in one of the items listed above.
10) Consumer Authority: Written consent of individual. (Copy of signed consent must be faxed to Docusearch prior to the request being filled.)
You will be required to select a DPPA Permissible Purpose when placing your order. By inputting your response, you are certifying to Docusearch.com that you are in, and assume full responsibility for, compliance with the DPPA and you agree to indemnify, defend and hold Docusearch harmless from any breach of the DPPA by you, your agents or contractors and any damages, fees and costs associated therewith. Information from this file may not be used to determine a consumer’s eligibility for credit, insurance or employment, pursuant to the Fair Credit Reporting Act, (15 U.S.C. Sec 1681).
If you are in compliance with the DPPA, then you can order a license plate lookup from Docusearch. As licensed private investigators, we have access to current vehicle registration information on file at your state’s DMV, so you can be confident that the results are up-to-date and accurate.
DPPA Q & A
Q- How does Docusearch verify that the DPPA Permissible Purpose I select is valid?
A- We don’t. By selecting your response, you are certifying to Docusearch that you are in, and assume full responsibility for, compliance with the DPPA and you agree to indemnify, defend and hold Docusearch harmless from any breach of the DPPA by you, your agents or contractors and any damages, fees and costs associated therewith.
Q- Who sees my DPPA Permissible Purpose selection?
A- Only Docusearch. However, if we are audited by any governmental authority or if any criminal or civil litigation arises as a result of your search, we are compelled to provide your identifiable information, including the DPPA Permissible Purpose you selected.
Q- Can I get into trouble for selecting an invalid DPPA Permissible Purpose?
A- Yes. If, as a result of any criminal or civil litigation, it is determined that you obtained protected DPPA information under false pretenses, you could be held criminally and/or civilly liable.