Since it is so easy to break a rights sale arrangement, where are all the examples?
Who said it was easy? There are certainly damages. So if Tom Selleck just decides to break his contract with CBS and not film Blue Bloods, the damages would be huge. His status on the show means it would effectively have to end. But, no court would force him to perform the contract. The courts avoid anything that looks like involuntary servitude. On the other hand, if some more minor character actor does the same thing, the damages would be minor, as the should could go on more or less as it was.
It's the same with the GOR. If UT, Michigan, USC or say Notre Dame with NBC break a contract, the damages would be massive, as those properties cannot reasonably be replaced (in ND's case it is the sole content provider, and so definitely can't be replaced). But if you replace Iowa State with BYU, have you lost anything? If you replace Wake Forest with UConn have you lost anything? Damages need to be proven, actual damages. I'm sure there would be some, due to inconveniences caused, but in both those latter cases, they would be small. Much less than the ACC's prior $50M exit fee.
The ACC has the same problem with the $50M exit fee. Liquidated damages are generally ok, if they are not punitive and are a fair approximation (at the time entered into) of actual damages. Where Maryland can be replaced by Louisville, $50M is absolutely punitive. The damages to the ACC are far, far below that. If North Carolina had left, and UConn, Cinci and UL were off the board, so UCF got the invite, the $50M would probably stick.
So the benefit of the GOR is not that it is iron clad, it is that it provides an effective sliding scale by value, making it hardest for the most valuable properties to leave. In the Big XII's case it really locks in Texas, and in the ACC North Carolina, Duke and maybe FSU, which is what the network cares about. If you look at the SEC, it doesn't have or need one for two reasons. First nobody wants to go, and second, none of the programs stand out dramatically. Florida, Georgia, LSU, Bama, A&M, those are all pretty similar, and Auburn, Mizzou, SC, Tennessee, Arkansas, UK and Ole Miss aren't that far behind. Miss State and Vandy are probably the least valuable, and that also makes them least likely to walk.