Why would anyone go to the trouble of growing and cultivating if bags were available at the liquor stores? I don't see too many stills around these days 'cuz it's easier to buy jack than to make it.
The only difficult aspect of growing marijuana is growing it indoors to evade detection. If people could grow it outdoors, legally, it would be quite easy and cheap to do; much more so than distilling liquor. No exploding stills to worry about, either.