[adanto6840]

Home sales, including home ownership data, is public in most (all?) of the US.

Even without providing your address, many US county government websites (the Recorder's office, Clerk's office, etc) allow for online lookups by name.

This is precisely how RedFin, Zillow, Trulia, and the like are able to obtain that same data...

[kelukelugames]

That is not how Redfin works. Nor is it how Redfin is spelled. Source: I worked there.