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
The claim that the title insurance industry is the reason for lack of adoption of Torrens title schemes is uncited, and immediately followed by descriptions of several cases where Torrens title was adopted (often poorly) and later abandoned.
I think you misunderstood the post you were replying to. Torrens title was invented in Australia. Just like in the US, land titles are a state responsibility in Australia not a federal one. But each state has a central statewide land registry which is the authoritative source of truth for land ownership. By contrast, US states hold land title records in a decentralised way (at the local government level not the state level), and those records aren’t legally decisive.
Most common law jurisdictions have centralised land titles, but often centralised at one level below the national government.