@Kireato
Because the author sacrifices realistic outcomes to avoid tragedy. At the same time he wants to have these precarious situations to create suspense and drama. You can't have your cake and eat it too.
I am almost certain a deus ex machina development will take place in the following chapters to save the girls (hopefully I am wrong). Some new hidden power will be revealed, or courage will prevail in the face of impossible odds or some bs like that. It is simply poor writing, since if you know that nothing bad will happen, there's no suspense in the first place, so you just ruined realism.
I get that the manga is going for a rather lighter tone even if it deals with more serious issues. It just feels pretentious when such scenarios unfold unrealistically. There's only so much you can push suspension of disbelief.
Don't get me wrong, I quite like it despite its flaws, it's very good compared to a lot of stuff in the same genre (*cough* isekai fantasy garbage *cough*). However that is no reason why it should not be criticized. The people on here don't criticize it just to take a shit on it, but because they realize it could have been even better in terms of writing.