Besides, editing shell scripts is not a gui-based approach anyway, so even if it did work it wouldn't actually solve the problem. On windows, you just set the settings and you are done. Same with anyone using randr. But for Nvidia there is no purely GUI-based user-level solution.
Of course, even if it did, that still leaves the question of why Nvidia can't just support randr 1.2 like everyone else. It also leaves the question of why they said years ago that it would be out soon, why they they said years ago it was a "top priority", then later admitted it was never a priority and probably never will be.
This is part of the problem with Nvidia's approach. They don't even begin thinking of trying to work on support for something until a stable version is out. That means you are left with months, if not years, of it working with every other driver until Nvidia finally gets around to working on it.
It took something like 6 months after KDE 4.0 was released before Nvidia finally got around to fixing crippling bugs in their drivers, bugs no other drivers. Heck, it took a month or two until they even admitted the bugs were their fault. The bugs had been known for at least that long beforehand during the beta cycle, but Nvidia said they refused to even look at the problem since it was still beta software.