A reader writes:
It's been a long time since I was a pothead, but in the old days a lot of us assumed that pot was getting stronger as a direct result of the drug laws. The penalties are based on weight, not on the amount of THC in the pot. So if you can get more bang out of a certain mass of weed, you're better off.
When I was smoking we were mildly cognizant of the line between simple posession and intent to deliver. I think that you get charged with the latter for a few reasons - if you had your weed divided into a number of plastic bags, or whatever. But there was also a weight limit. If you had more than such and such an amount, it was intent to deliver.
If alcohol were illegal, and the penalties were based on the fluid volume of the booze, no one would drink beer. It wouldn't make any sense.