I assure you that “old cars costing as much as new ones” isn’t the result of the market force of people reading contractual fine print and/or freaking out about telemetry. Concentric circles of echo chambers over here.

The main reason is more tangible to people. It is more reliability and simplicity. For instance the Toyota Tundra used to have a V8 that was pretty bomb proof. But over the years, manufacturers put in more efficient but more prone to problems turbocharged smaller engines. The bearing clearances went down, thinner oil then can be used which is also more efficient. But the margin for error when you are putting what used to be a performance engine in a car is much smaller and there have been issues. As car prices have gone up, people value a time tested drivetrain. There have been a lot of problematic CVT transmissions too.

I agree. I have never met anyone in real life that's concerned about telemetry on their car.

They're worried about the cost of a new car, and the cost of all the electronics, should they go bad.