I pick up hitch-hikers when I'm back home in Maine. I trust people too much maybe but there is never a time when I don't have some sort of weapon on me. But mainly I've been there before, stuck in a jam, and had to walk. Usually I'll just stop and ask someone walking if they need a lift before picking up a scruffy looking person with his thumb in the wind.
I never do it when I have my wife or kids with me, and my wife gets mad about it every time I do it. I can sympathize with people, whether they ran out of gas (done it) or they lost their license (done it several times).