It really depends on the particular area in question. I suppose the short, not-very-useful answer to your question is "yes, probably". In many places this kind of information is "public", but not always readily accessible. Or when it is accessible, it has to be cobbled together from multiple sources.
Getting a large, quality layer of ownership can require a bit of work, which is exactly why folks are willing to pay third parties to do all that work and just get access to the resulting data.
Is there a particular state/county you're interested in? I would start with whomever handles property taxes for the area to see if ownership information can be FOIA'd, or if they have any kind of open data.
- Josh Carlson
Kendall County GIS