Yeah, I notice that the guy with not too much marijuana in his car in the example has percocets, an addictive narco. That's the problem is that people keep lumping everything together. Alcohol is far more of a problem than marijuana in this country, more deaths from it by far, and tons of arrests anyway. I would say that of the penalty for a joint and the penalty for an open beer, the beer costs you more in my experience. Alcohol just happens to be legal, frankly it should be illegal also. There's certainly no societal good that comes out of it, it's addictive, and drinking and driving kills. As the old argument goes, you can't overdose on marijuana.
You do make a good case why marijuana shouldn't be legalized. As you say, alcohol, which is legal, causes far more accidents. I can't imagine how many more accidents, and deaths, would be caused if marijuana were to be legalized.