its been a few years in my case, but iirc The idea is that the certified letter gets returned to you with postmaster notes stating it was undeliverable ( could not be signed for essentially ) within 30 days, severing the last known way to contact the previous title owner. In my case my first letter was lost, and my second letter was signed by his executor. Which flopped my title quest on its head because I then had to speak with him and hope the owner was willing to let me have it……since I’m such a nice guy they said yea, we have no use for it, we’ll get a duplicate lost title and fedex it to you signed, whew it sucked.
in reality there shouldn’t be a way to scam that step, or say “ yea i did it “ without documentation — the DMV either has a copy of the returned certified letter that they can see and verify when you hand it to them, or they don’t.