Earlier quoted context omitted.
That's actually a problem with all modern cars: If the battery dies, the key fob won't open the door. In fact, if the battery dies in the car or the fob, you can't open the door. But, there is a mechanical backup with an ordinary car. In my 2012 Volvo, I can open the driver's door with the mechanical key. If the fob is ded, I can physically insert it and start the car. If the car is also dead, I have to sort that out…
If the battery is flat on the car then you are still pretty much out of luck even if you can get in. The only advantage to being able to open it is to use it as shelter in a emergency situation
With an EV yes, but not with an ICE. Just keep a jump box in your trunk.