I do believe that hitchhiking has changed because society has changed. During Chris's adventure and in earlier times people were a lot more trusting because not as many crimes or crazy people were out there/known about. Picking up somebody along the side of the road was an act of kindness. Nowadays hitchhiking is more dangerous because people in society are more dangerous. Being able to be picked up while hitchhiking is also less likely. There are bunch of movies out and stories in the news about hitchhiking gone bad and killers posing as people who just need a ride. This freaks people out making them not want to pick up people off the road, not out of rudeness but fear.
I for one would never hitchhike or pick somebody because of the fear of being trapped in a car with a crazy person and not being able to help myself. But for those out there who need a ride, can defend them self, and can trust people, hitchhiking can be helpful. It gets you where you need to go and helped Chris continue on his journey. Without hitchhiking I don't think Chris would have made it to a lot of the places along his travels.