One reason may be that the newer cars have many safety or nice features.
You can get ones with many cameras on them and some that you can set to follow at a distance a car in front of you and some that automatically put on the breaks if it thinks you will be in a collision.
I talked with a salesman that was trying to sell a 3 year old car with only a few thousand miles on it. It had belonged to the wife of an exective of a large company. Her husband told her it did not look for people of their position to drive a car that was more than a couple of years old. Thatg was back when one could usually tell a make and year of a car from a block away. Now they look very similar to each other.