I don't need to get into an argument over people's perceptions, this exercise shows that cheap cars don't stick around to be sold on, while more prestigious brands do.
No argument from me, in the age range chosen you are almost certainly correct. Pre-2000-ish expensive cars have tended to survive better than cheap ones as they are still fundamentally basic engineering, albeit with some fairly rudimentary electronics added on top (much of which can actually be repaired with a soldering iron and a multimeter, or at worst an oscilloscope, especially if there is a worthwhile owner's club).
As the electonics get more integrated, and the mechanicals become more complex (think DSG, electronically controlled differentials, ECUs comprising multiple bespoke ASICs etc.) the possibilities for economic repair diminish, and survival seems to be favouring the simpler, more plentiful examples, especially where the electronics are less integrated.
Conversely, the parts which can usefully be re-used from a complex car with deeply integrated electronics seem to be reducing in line with the number of mechanics who are willing to work on them, as swapping mechanical parts often needs to be combined with some element of control unit reprogramming.
This is not a fixed rule, more an observation related to running, operating and monitoring a fairly wide range of vehicles.
As a trivial example of the effect, consider Fiat's Dualogic gearbox actuator. It is actually a simple device, but confounds many who fall foul of a problematic one because it is mechanical, hydraulic and electronic. So, even though it is fitted to a fair number of vehicles, there are only a few places who can actually fix them (as opposed to places who can fit a whole new unit, as long as they are available), thereby often causing the scrapping of an otherwise fully working car. (Ended up being simpler to learn how they work and get the spanners (and computer) out myself)
Going slightly off-topic, I have also struggled in finding independents who will work on DSGs, even for fairly high value cars, so any recommendations in Eastern England gratefully received. I have a Ford DSG which can only select reverse and it is baffling me...