Reality is quite a bit more complex. Batteries do go bad when usage is bad. Rapidly. Fast charge to 100% every day, and see how it holds up. Hint: it won't.
What changed is that now we have mechanics with experience in battery management who will take a look a deep look into the battery data that they will pull from a modern BMS (which have improved massively in last 10 years), compare it to how it should have aged and will be able to give a detailed reports on how this car's battery holds up.
This means that people who do retarded shit to their EVs now struggle to sell the cars, while responsible owners who keep batteries in good condition can now charge a bit of a premium on used market in most developed nations (and increasingly, quite a few developing ones).
So in summary, this is about evolution of BMS coupled with emergence of experienced cadre of specialist mechanics who specialized in automotive batteries, their service and repair. You still shouldn't trust old batteries. But now, you have ways to verify.