Is horribly underreported how worse the ev batteries become after 5 years.

That is because there is so much variability. The software of the battery power electronics is paramount to battery lifespan.

That is, how fast and deeply you discharge your battery and the way you charge your battery both dramatically effect lifespan.

It turns out that active cooling (liquid cooling systems and radiators) are vital to both fast charging and battery pack lifespan. See the early Nissan Leaf that had battery packs without active cooling systems. The battery had a truly disappointing lifespan. Now Nissan doesn't make them like that.

That said, it would be a relatively simple matter for the manufacturer to build a diesel heater into the battery cooling system. That would keep the battery warm in low temperatures. Even electric heating driven from the charging circuit (an electric blanket) that ran while the car was plugged in would be a good start.

It amuses me to think about people pouring diesel or kerosene into their electric car to keep it warm. It would solve a bunch of problems, as making heat out of electricity is really inefficient, so passenger cab heating, windscreen defrosting etc takes a huge toll on the battery and thus the range.

IMNHO, EVs are just an under-baked idea. They will get dramatically better as these problems come to light and are solved.

tl;dr: It is just about impossible to do an apples to apples comparison across EV brands or even models.