Is this born out by real life examples? Is a 2025 Model 3, for example, significantly different technologically from a 2020? Definitely does not have double the range, and the technology has evolved only slightly in that time. The heat pump was introduced in late 2020. (and to be honest, heat pumps have turned out to be less of a slam-dunk than we hoped, they have a minor effect on range for most people)

Not double the range. But you could get one with an LFP battery now that probably has about double the life time in terms of cycles. Closer to 3K cycles rather than 1200-1500 cycles for the NMC batteries common in 2020.

Fun fact, the 2020 model 3 would still have its battery under warranty. That's true for most model 3s with the exception of those that did more than 100K miles or the ones that were sold in 2017. Those would have just started coming out of the eight year warranty. But most of the second hand model 3s are still covered by warranty for their drive trains.

Mostly, second hand buyers can get some decent deals on their cars now and don't have to worry that much about their cars depreciating massively when they sell them on five years later. With EVs most of the depreciation happens in the first few years.