2. I don't even understand how a title transfer could happen without verifying ownership. Is the title system in the USA decentralized or that much different than elsewhere? i.e. Torrens-style
These scammers will either (a) start with a stolen identity and see what land that person owns and try to sell it, or (b) find an interesting piece of land and steal that person's identity and pretend to be them.
In either case a 'definitive' database (or lack thereof) is not the problem.
Ontario and BC (e.g.) in Canada have a land registry:
* https://www.ontario.ca/page/overview-land-registry
* https://www2.gov.bc.ca/gov/content/housing-tenancy/real-esta...
That hasn't stopped fraud (attempts):
* https://www.cbc.ca/news/canada/toronto/three-charged-stolen-...