My S acts the way you are discussing here - even if the key isn't anywhere in sight, I can unlock the charge port door with the button on the charger handle. My X does not act the same way. My X needs to be unlocked or the charge port door will not open. I often have to use my phone in the garage so that I can plug the X in, and never have to do so for the S.
Maybe it's a specific issue for my car, but I know
@K-MTG also has an X so that could be the source of his claim as well.