We bought a used Toyota and they somehow found us when there was a recall. I've wondered if it was getting the car registered at the state level. Come to think of it, I got a recall notice for an Oldsmobile without contacting GM. They found me. Again, it must be from getting the car and its VIN registered with your state. Hopefully someone chimes in with the appropriate answer as I'm also curious.
I registered on the Chevy page and on the app. Not sure if the previous owner did as well but I had no problems. For recalls, the app and Onstar will let you know and for warranty repair, it's transferable so I would think as long as you have the registration (if they even ask).