It's not really a preference if it's only what you can afford. People who only buy second-hand cars will naturally end up with whatever was new 5 years ago, which will gradually include more automatic ICE cars, hybrids and EVs.
not 100% disputing what you're saying and im sure more automatics/EVs etc will gradually filter in. BUT it's not just an affordability thing lots of people just prefer cheaper cars and would prefer to put their disposable income elsewhere.
Preferring to put your disposable income elsewhere sounds exactly like an affordability thing.
If I have £15,000 in the bank, spending £8,000 on the manual vs. £9,500 on the automatic (Renault Clio, 5 years, both on motors.co.uk) is significant. I'd choose the cheaper car.
If I have £50,000 in the bank it's much easier to justify.
(And if I have only £8,000 or less I don't have a choice, but I might tell my friends I "prefer" not to put a lot of money in the car.)