There was a post on the Alien RPG Discord where somebody basically said, "Characters with military background should get a lot more starting skills than other characters, because in the military you get trained in all these things."
Totally ignoring how true that is, how would that possibly make for a fun game?
I think the same thing applies here. We could make all kinds of realism arguments about these characters, based on their backgrounds should be able to do, but would that make the game fun? For example, your argument could be flipped to argue that Wizards, with their magical training, should be an order of magnitude better than Fighters at saving throws versus spells. But if you actually modeled that, Fighters would almost always fail their saves, and Wizards would almost always succeed. And that would be bad game design.
Fighters are a little bit better than Wizards at both resisting and imposing grappled, etc. You've got to let your imagination fill in the rest, instead of trying to model what you think reality should look like.
Or not. But that's my advice if you want to enjoy the game. You be you.