The cities don’t normally send out anyone. The buyer pays for a survey and the bank and title company will check for encroachments.
It depends when the garage was built. If before he purchased the property then title insurance may cover him. If it was built after then the permitting process should have covered it. The survey company may have liability.
Of course he may have just built the garage without permits.
I think the news video showed a copy of the permit and the dates signed, it was quick, but I think that was what was shown.