my point was not to bring up legal weed to say it's at all a reason for the disappearance. My intention was to illustrate that, in fact, smoking pot isn't a big deal - all sorts of people do it here but - getting back to my original point, those that do partake responsibly (like I do) try not to drive after consumption, so going out to "after party" with someone, if that would involve imbibing, would be a valid reason to leave your car at home. That's where this conversation started in the first place.
I think on these forums, especially with readers from around the world, it's important to set context about the environment the incident took place in. Plenty of folks smoke weed around here and we leave our cars at home - most of us are normal people. There are still plenty of communities that believe that weed is evil and linked to all sorts of crazy stuff.
ETA: and just to be clear - we haven't seen any evidence of any use of any substances other than alcohol and of the videos we have seen I don't see intoxicated behavior.
I think running through scenarios of why someone would leave the house without their car, after midnight, could help uncover ideas/leads.