https://www.statista.com/statistics/261877/average-age-of-pa...
It's true they don't look great underneath...
Stop buying bad cars.
Conversely, there are many engines on there noted for their reliability, Ford Modular V8, for example, GM LS1, Ford Model T engine, VW Air-cooled Engine.
Don't forget, just because a typical owner may sell a car after 5-10 years, doesn't mean it goes away into the aether :).
[FWIW, I have a 2004 Subaru WRX; I make the dealership rounds every year looking for replacements, and cannot find anything that handles better in that price range - in fact, by all accounts modern WRXs are a softer drive]
A long tail on only one side (no car has a negative age) means that more than half would be older than the average. You were thinking of the median, not the average.
It's really mostly the macbooks that are terrible in this regard.