The age of a car has very little to do with whether anything works or not.
I totally agree to a point... Bearing in mind most of us would maintain our cars properly, a lot of people who aren't enthusiasts would not... and generally older cars are neglected more, because the people who drive them, do so because they are cheap.
Rovers for example. Every Rover we have owned, barring a concours 800 coupe, and a new-ish 75, has been bodged in some way by the last owner. Because the car is not worth anything, people aren't willing to spend any money on them.