“Normally it’s routinely recharged from the EV’s main battery (to account for the fact that an EV doesn’t have an alternator to charge the 12V battery like an ICE car does). But that doesn’t happen when the driver drives it to empty.”
Wouldn’t the 12v battery stilled be fully charged at that point and still last for many hours?
Not if the driver is running the AC and such. The AC and heat in an EV comes from a heat pump since there's no engine turning a belt to turn a compressor like in an ICE.
The bottom line is not to let the EV battery reach empty. And just in case, have jumper cables and/or jumpstart battery. And most important, know that it's what has to be done in that situation. Or another way to put it, be prepared in an EV like you should be in an ICE.