When you are older everything is time and knowledge. This is an okay way to travel but, what about the out of the way things. The young ones, because they don't have a lot of money, tend to discover more. This is because they don't have the money to take a taxi cab. They like to get lost.
Adults are more schedual oriented.
They bring a lot of bags full of the amenities and are not prepared for the back, foot and head aches that are coming to punish them, not to mention the pocket book ache when you run out of BellBoy payment. And Americans tend to skip the experience of why we travel by doing things like wasting time money on renting cars. Don't get me wrong, renting cars can sometimes be good if you are doing research or need to go to far out places on your own time. Not to get confused I am an American but in all my travels my family only rented a car once. This was because we were going to places that were a good distance from a train station or bus stop.