This is an interesting and valuable comment, but I think, with regards to the particulars of the bill, that you're confusing the common sense positions of most pro-19 people with the actual details of the bill.

Prop 19 was spectacularly flawed. Among other things:

* It created a new protected class of employees in California with a clause that said "discrimination" against pot smokers was unlawful, modulo only circumstances where an employer could claim marijuana was actually harming job performance. The bill actually says that! Race, color, religion, gender, national origin... and pot smoking.

* The bill was remarkably fuzzy about the driving issue. Yes, it says you can't smoke and drive. But it also created circumstances where you could clearly be under the influence of marijuana and operate a motor vehicle.

In both cases, the underlying motivations behind these egregious overreaches seems to have been the concern that MJ metabolites are long-lived, and people would get fired or lose their licenses for smoking several weeks ago. At least as regards the driving situation, that seems like a valid concern... but the answer to that problem isn't a law with gargantuan loopholes.

Prop 19 may have lost in part because its campaign was incompetently run, but it also lost because the proposal was incompetently written. And those two issues fed on each other: read the political analyses to hear about the pro-pot groups that sat this one out because of the flaws in the measure.