I'll challenge your assumption that there aren't many cars on the road more than 10-15 years old, since my two are 15 and 27 years old, and cars this age are far from rare hereabouts (western US). Of course this can vary: if you live in the US northeast, where they make a practice of spreading corrosive chemicals on the roads, your car's body might fall off in a few years.

I'd add two reasons to yours. First, there was a period of a couple of decades where few if any new GA airplanes were built, for fear of liability. Second, planned obsolescence: auto makers come out with "new" (that is, different sheet metal) models every year, so that the gullible will buy the new designs in order to follow fashion. That's hard for aircraft makers to do when the basic shape of the plane is dictated by aerodynamics rather than style. The much higher price for a new plane only makes it harder still.

I'll challenge your assumption that there aren't many cars on the road more than 10-15 years old, since my two are 15 and 27 years old, and cars this age are far from rare hereabouts (western US). Of course this can vary: if you live in the US northeast, where they make a practice of spreading corrosive chemicals on the roads, your car's body might fall off in a few years.

I'd add two reasons to yours:

1. There was a period of a couple of decades where few if any new GA airplanes were built, for fear of liability.
2. Planned obsolescence: auto makers come out with "new" (that is, different sheet metal) models every year, so that the gullible will buy the new designs in order to follow fashion. That's hard for aircraft makers to do when the basic shape of the plane is dictated by aerodynamics rather than style.

The much higher price for a new plane only makes it harder still.