I know that in Japan, China & Korea along with SEA including the Middle East, it’s definitely criminalized and you’ll get arrested for bringing in weed (they’re indifferent whether its for medicinal or recreational use) since they do not allow it on their turf. In some countries, that guarantees a death sentence as they have zero tolerance on allowing those substances. It’s not like let’s say Canada or Germany where weed is tolerated.
Travelers who are weed users aren’t stupid to travel internationally with cannabis as they’re aware the rules are different across borders. Then, if they crave for weed (but can’t consume that as it’s a crime in those countries) what’s the alternative? Over the counter pills, maybe? Other valid substitutes that may give off similar vibes. I’ve heard a case where an American couple had their weed confiscated in Australia, where it’s illegal.
if you smell/see it, ask where they got it. tactifully, make friends with them. don’t sound like or be like a pig/snitch.
iirc the chinese use it as a sleeping aid, but they are not fond of druggies because of that whole opium thing. ymmv depending on where you are, don’t be dumb.
respect your intuition. if you are not confident with it, just fucking don’t.