I've been without a car, and truding along on foot makes one appreciate folks willing to stop and help you out.
I will almost always give someone a ride that I see asking for a lift.
+1
In the mid 90's I hitched through Scotland when I lived there in college armed with only a folding knife for protection.
I have hitched in the States a couple of times.
I would say that I often give rides to people but it is COMPLETELY situational. I would likely have given the guy in the example a ride, but I would have had to have been there to get the "vibe" from the person.
In the last year I've probably given 10 people rides. I have some funny stories. I often give rides to people in ski towns, but these are clearly skiers going to the bus stop. Once I gave a guy a lift in Breckenridge on a 10 below freezing night, he was walking a mile and it was unbelievably cold. He turned out to be a bar & grill owner and bought me a nice dinner for my trouble. Some friends and I picked up a backpacker on a cold night in Breck and drove him a few miles. He was an odd character for certain. I've picked up a couple individuals at the entrance ramp to the highway.
It is situational though and I have NOT picked up a lot more than I have picked up. It depends on the location, the way the person looks, their gear, the "VIBE" they give, time of day, etc. If it's late, in a bad area, they look rough, etc. I won't pick them up. It also depends on who is with me, whether I'm armed (almost always am), if I'm in a hurry, if I can safely stop, if I have room in my vehicle, etc.
So, it really just depends, many times yes and many times no.