This is the real answer. When they illegalized a drug that was already widespread and in common use, basically everyone simply became a criminal. There’s no reason to think people’s natures will have changed enough to suddenly want to be law-abiding citizens, easpecially when they’re on ceffeine withdrawl.
I don’t think it would be as widespread though, since you need specific caffeine producing plants in order to get it, as opposed to alcohol which can be made from just about anything. The growth and distribution would probably be more like Marijuana, if 90% of the country were addicted to it (so insanely expensive and a whole lot of also caffeine-dependent cops being paid off).