"Public records" means data generated by the government that are available to anyone. Drivers license registration, voter registration and participation, county auditor databases, arrest records, etc are all accessible to anyone (usually a nominal fee is involved, may also vary slightly by jurisdiction). People aren't "actively" creating these, it's a byproduct of government transparency and public oversight.
That's what I'd take it to mean too, but the parent mentioned spokeo, which made me unsure if they were redefining the term to include anything public as they appear to harvest data from social media too. Official records are for most people pretty static, more familiar and more predictable than social media, and thus less dangerous, at least imho.
