GTA:SA re-rated as Adult Only

GTA: San Andreas is now re-rated as an Adult Only title, by the ESRB under the pressure of US senates because of the Hot Coffee sex scene mods for the game. What I really don't understand is, why is this happening? Is having sex more serious than doing drive-by shooting, or beating up police senselessly in the game? Why I don't see people in real life get jailed for having sex (almost everyone got to have sex in life, just the matter of time) But instead get jailed for doing the other stuff which is the norms in the game like knocking down pedestrian with your car, heisting the bank using explosives, and many more. And sex is the achilles heel for this game to get re-rated as Adult Only, but not those criminal stuff. Why??