Sony has a "lock out" code that prevents a region 2 PlayStation game from playing in a region 1 PlayStation console. This "lock out" code also exist for movies and DVD players (including the DVD drive on a computer). The game or movie verifies that it's in the proper machine before it will play. This region code "lock out" has been around since the first PlayStation and since the beginning of movies on DVD's. Sony has successfully won cases against makers of mod chips that attempted to by pass this "lock out" on their PlayStations.
Sony also has a "lock out" code on their PlayStation consoles that detect a copied game. Only an original game disk will work on a PlayStation. Gamers have cited that "fair use" allows them to make back up copies of their games. But these back up copies will not work on their PlayStations. Makers began selling "mod chip" to bypass this "lock out" so that burned back up copies of PlayStation games will work on a PlatStation. Sony sued these "mod chip" makers and won.
Quit citing the Lexmark DMCA case as though it's some kind of landmark case that proves that copyright holders can't use the DMCA as a means to "lock out" unauthorize use of their copyrighted material. Lexmark didn't have a case because they didn't have a legal copyright on the chip, that they were using to verify an original toner, to begin with. And even if they did, reverse engineering is legal in some instances. Sony and Apple have legal copyrights on their IP. They can use the DMCA to enforce this copyright. They can "lock out" their copyrighted material anyway they see fit.
It doesn't matter that OSX will work on a generic PC (with a little tweaking). A Sony region 2 PlayStation game will play perfectly on a region 1 console if it weren't for the region "lock out" code. A burned copy of a PlayStation game will play like the original if it weren't for the built in software that detects a burned copy of a game. A region 2 DVD movie will play just fine on a region 1 DVD player if weren't for the region "lock out" code.
Buy a Dell, HP or Sony PC and you get a disk with an OEM license of Windows. That disk with Windows in it will not install Windows on to any other PC of a different brand. And most likely won't install on to a different PC model of the same brand. You are essentially "locked out" from using your OEM Windows license on any other PC, except the one it came with. (Apple does the samething with the OEM OSX license that comes with a Mac.) You can't legally do anything about it because that's the terms you agreed to when you first started up the computer. That OEM license is non transferable to another computer. Even if you destroy the original computer that came with it. You can not legally sell this license. (Even though you see the disk on eBay.) It's usually stated right on the disk or the case it came in, "Not to be sold separately", "Only to be included with a PC".
A OSX upgrade license that you buy off the shelf is like that OEM license. It's only meant to be used in a certain restricted way. That OSX upgrade license requires you to have a previous OSX license before you can use it. And just like how that OEM license can "lock" you out when you try to load it on a different brand PC. The OSX upgrade license can "lock" you out if it doesn't detect a previous OSX license. (A Windows upgrade disk will also not install until there's proof of a previous license.) That is why it's stated on the box that you must have a Mac to use this upgrade license. Every Mac that it will work on came with a previous OSX license. Apple is not doing anything illegal or anti-competitive because OSX "locks" you out when you try to load it on a generic PC. Did that generic PC have a previous OSX license? I don't think so.