Here in the states, you can get from as small as community service or paying a fine to being in jail for an undetermined about of time (that's decided by the judge at trial, I believe). It also depends on which state you live in. California's pretty lax on it, while other states are very uptight. I am not in California. :[
Sadly, there is an awful lot of ignorance to a lot of things, not just cannabis. Hell, most people just say "I hate drugs, they shouldn't exist!", in which case I have to point out their dumb****ery in the fact that all those medicines that save people's lives are drugs, and by taking them away everyone is really screwed. :/ Then they sort of stumble and say "well, only the illegal ones!" when quite a few illegal ones are illegal for the reasons you pointed out. Money, mostly. Money money money. And association.