I have not used either, but I regularly use a commercially-available database called TLo (what used to be called AutoTrack in the early days of the internet). I think those systems you mentioned are pay-as-you-go versions of TLo that are available to anyone with a credit card.
TLo is run by TransUnion, one of the three major credit reporting bureaus. It's used by law enforcement, though only for research/background purposes: everything we find on there we need to verify by other means if it's to be used in court. Otherwise, it's just an investigative tool, i.e. to find someone, find where they work, etc. Suffice it to say that with a license plate number, someone in that system can find out everything about you, to include your SSN, addresses, etc. It's supposedly all "unverified" info, but back in the day when I worked for a different agency and worked identity fraud cases, we were actually encouraged to run ourselves. It was so accurate that it scared the sh^% out of me.
And you don't need to be a "crooked cop" to get into it, either, because this system is (apparently) available to anyone who can articulate a need and is willing to pay for it. From their own website, TLo's customers include people working in the following fields:
Collections
Corporate Risk
Financial Services
Government
Insurance
Investigative Reporters
Law Enforcement
Legal Professionals
Licensed Investigators
Repossession Industry
Skip Tracing and Investigations
That encompasses a LOT of people with potential access. Add in everyone THEY know and "a lot" goes up exponentially. Moreover, many of these folks may not have any controls on what they look at. I have to log in everyone I run and it has to be for official purposes. Think that happens with everyone else on this list?