Yeah, but society has come to a consensus that it's okay for bartenders to serve liquor, and even then, there is legal liability on the servers part as far as how much they can serve you.
Society has also come to a consensus that selling prescription drugs illegally for recreational use is not okay, and there's a huge amount of culpability on the part of the seller for the damage caused. That's why sentencing for dealing is generally much more punitive than for simple possession. That's why, as you stated earlier, you get in a lot more shit if a junkie dies on your living room floor after consuming pills you sold them as opposed to walking out your door alive.
But go ahead and call me an idiot again, you're clearly an amazing human being.