You make good arguements that prohibition of alcohol was a colosal failure. It made law abiding citizens instantly turn into criminals over night. (I'm talking about consumers here.) Because you took a product that was legal and widely available, illegal. But there is a difference here in that marijuana although legal at one point was not widely used when it was made illegal. I don't know your experience with marijuana. I had some experience with it (I did'nt inhale
just kidding) and it seems to me it's purpose recreationally at least, is to alter your sense of reality. You may argue alcohol is similar, but there are sutle differences.
1. Like you mentioned with tobacco, pot smoke and it's use affects those around you. Even if you choose not to smoke, if you are stuck in a room where someone is smoking, you are affected by second-hand smoke. If your drinking, you need not involve anyone else. I'm talking kids here.
2. Drunk driving is a serious problem. Right now, accidents involving pot intoxication does not appear to be a problem, but part of that is because alcohol is also a component, and it is easier to test a violator's blood for alcohol. How many of those drunk drivers have also been under the influence of pot? Unknown. I think driving under the influence of pot can be worse, because there is a component of paranoia, and dilation of pupils affects vision, particularly during daylight hours.
3. Fire. The most common way of consuming pot is to smoke it. You have now added fire to the equation of someone who is under the influence of a drug which impairs your attention, and memory. A bad comination for someone just sitting in his livingroom. Let alone putting someone behind the wheel, camping in the woods, landing aircraft, you name it.
4. Moral issues. What ever your opinon of God or even your own conscious. What message is sent to kids about legalizing pot? I don't see any upside here. "Son they are legalizing pot, because we just can't win this war". "We just gave in to the drug dealers". "You can't win them all". "Maybe some of these other laws we don't follow we will just give up on as well". It may be a small thing, but it can lead to other things. Actually, it has already......
The speed limit merely a suggestion, more of joke unless the CHP is behind you.
Agreeing to pay your morgage is out too. Just wait for the government to bail you out because you forgot to read the fine-print on your contract. Just walk away, the rest of us will pay your bill.
"Let's not give letter grades to kids, cause some will feel bad about their grade".
At some point it affects society in a negative way, inspite of what you think about the cost of enforcing law, the alternative is worse.
There I go fear mongoring again. Sorry