You mean it's wrong because stunt actresses are sometimes allowed to wear something slightly different... but right because in the instance you thought of, they precisely were allowed not to wear high heels?

OMG, that's like... the original sin of Hollywood. Everyone is always so clean and has perfect hairdos and make-up, no matter the circumstances... Like even the apocalypse is no excuse to not look your very best.
Two particularly egregious instances come to my mind.
In Eragon (the movie), the protagonist is a poor boy having to resort to poaching to survive, but of course the actor is dressed in clothes that look SO new, I kept expecting to see the tags still attached...
In Planet of the Apes (the 2001 movie, though maybe all adaptations are guilty of this, I'm not sure), humans have supposedly devolved into wild animals... but the female human who gets close to the protag looks like this: