[Spooky23]

Biggest reason is risk and loans.

Cars typically have pretty predictable depreciation schedule but after you hit a certain point the car could be worth anywhere from scrap value to a few thousand dollars. Few banks are going to write a loan for a 10 year old car, insurance valuations may not cover the loan value in the event of loss and few qualified customers are in the market for an old car.

As a result, you’re limited to cash buyers and parts buyers. Cars that meet whatever the cash buyers value are worth a lot. Even minor variances from whatever the car/truck guys want will take the value from $5-7k to scrap.

State regulations have an impact as well. In New York, all check engine light issues make inspection/registration a no-go. Many repairs exceed the value of a new car. In a place where the state doesn’t do inspections, you can run a beater longer. That circles back to the finance issue - banks won’t write loans for cars that may be pulled off the road.