There was this Pre-Release-Testversion used by many games magazins that HAD AA!!!!! I don't know for what reason R* don't want us to use it, but it was there. And it worked. Simply watch the screenshots that were made with these Testversion.
A german magazin published a screenshot of the options screen (can't find the link), it had more tweaks than the retail actual has. And one option was Anti Aliasing."
A TESZTELŐK OLYAN VERZIÓT KAPTAK, AMIBEN VOLT ANTI ALIASING!
#21026