There is a generational thing, but I think it is only in how common hitchhiking is. I disagree with the idea that people were more generous way back when. When you were hitchhiking in high school, you did it because you didn't have the money to drive yourself. The person who gave you a lift knew that and didn't expect anything in return. Now we are talking about people hitching a lift while on vacation. They are doing it not because they don't have the money; they are doing it for logistics reasons (i.e. There is no easy way to get a car to your hiking destination). You are relatively well off (you are able to go on vacation) and if you are hitching a ride from someone who isn't, it is rather selfish of you to not offer to help split the cost of the ride. In general it costs someone $0.51/mile to drive a car according to the IRS.