My guess is the stark difference in type of cars, number of cars, typical miles driven, and public transport. A standard american's road trip vacation would be unusual in europe. For example, my relative visits family several times a year, doing 4 hour drive in a large pickup truck for a short weekend trip. In europe, my understanding is that destinations are likely to be closer, cars are smaller, and trains are common (maybe the default?).
https://www.eia.gov/dnav/pet/hist/leafhandler.ashx?n=pet&s=m...