Not necessarily true, Nick.
In a lot of cases, the seller (foolishly) forgets to erase and reformat the hard drive of the computer. So the OS, and every app on there, is still registered to them. I've seen plenty of occasions where Apple and independent Apple service providers would refuse to service or wipe a Mac that was clearly registered to someone other than the person claiming to be the owner. Apple has no interest in helping thieves, and might want to see proof of ownership.
I haven't run into this problem yet. Yes…in the last 2-3 years or so...Apple has started associating the serial number of a specific computer with a person's Apple ID. And when a used Apple computer is sold…the owner should "disassociate" it from their Apple ID (because I think that Apple only allows 5 devices to be associated with any single user ID). And who wants any of those 5 "wasted" on an item they no longer own.
But what I'm thinking about are two specific situations:
1. Purchasing a used computer…and having problems using my Apple ID on that computer.
* In the last 2-3 years I've purchased plenty of used Apple products have have had no problems with my Apple ID. And I know…the former owners of most of these devices had no idea they should disassociate their Apple ID's.
2. Walk into an Apple Store with a warranty issue on a used computer I purchased…and be refused service.
* Nope…has not happened yet. I'm talking more than 10 years (probably more) experience with purchasing used Mac's…that may have still had Applecare active on it…and needed warranty service.
In my experience…if a person walks into an Apple Store with a used Mac. …the first thing the Apple folks do is verify (via the serial number) if Applecare is still active. If so…no problems. They proceed with the troubleshooting & repair.
There has never been any mention of previous owners info. No questions asked of me how I came into possession of the computer. No suggesting or implying anything about thievery.
If you got it (used computer)…and walk into an Apple store with it (used computer)…it's yours. In my experience…Apple has never acted like the "Used Computer Police"!
- Nick