I am very skeptical too....for the reasons you detailed.
Ah, just did a little reading on these temp issues.
It seems that you “preheat” your EV ahead of time before you get in, using power from the outlet you are using to recharge your vehicle battery. I guess once that’s done, the on-trip power useage isn’t as draining. But still, you have to be constantly planning for all your trips. Too inconvenient.