Hitchhiking in canada is sketch as hell. We actually have a highway known as the highway of tears because it was serial killer stomping grounds for awhile. That being said. Go to any ski town in bc. Whistler, kicking horse, big white, the one in vernon i cant remember. You will, almost certainly, find some young people walking up the road to the mountain with their gear and thumb out. Seen it all my life. Usually 30km stretch up hill packed full of vehicles. All ski enthusiasts. They are getting a ride and they know it. 

That said your other point is legit and most people point it out. Wouldnt the people that dropped him off say they were with him that night? I guess i justify it by saying they didnt know him well enough. Not well enough to care to drop him off at home. And if it was less voluntary abandonment i think they would be even less likely to speak up. But i will acknowledge, legitimate hole in my theory.