if you fail, it should be he has a cut face for the game
Possible, but then that's another set of models / textures they need to make, and if nobody actually notes his face is cut, how important is it that you can go through the game with a cut face? And it wouldn't just be "cut face / not cut" you'd have to have a blend so that the cut recedes with time. This all costs money for virtually zero narrative benefit. Also, if you add a "face is cut from shaving but it recedes with time" set of texture blends, then that's specific to that
one shaving event, and people will wonder why other potential injuries don't also have the same "scarring system". And that would be because each possible scar would need to be modeled as a separate texture overlay on the model, eating up the art team's time and reducing the rendering speed in the final game.
And then remember, it's not just "cut face". That's just what
you thought up. They'd have to anticipate every individual thing that everyone on Earth would have thought you "could" do at every point. Which is nonsensical. if they'd added in a "cut face" branch for just that shaving scene, then that would have just been an "on rails" pointless detail anyway. And all those details would cost a lot, and just delay shipping of the game and/or bring in countless chances for bugs or textures or models fucking up. e.g. going into
that much detail on optional things would mean the project is a guaranteed failure before it's launched.
There's also the player's point of view. e.g. if an unimportant scene such as the shaving thing could cause a semi-permanent scar on the main character for the
rest of the game, you'll get 1-2 people who think that's cool, for 99 other people who get
pissed off and end up reloading the game from before the shaving event, until they get it first time without the scar. So, taking player psychology into account you can assume
almost all people would just reload the game if that happens. So then, you design it so that it merely makes you do the shaving thing again
automatically e.g. exactly what the game actually does. There's also another realism aspect here:
most people don't fuck up shaving and walk around with a cut face for hours, even if they went "ow!" it's usually not an actual cut that would really be visible. So there shouldn't be e.g. a 50/50 chance of that happening to you each time you shave in the game, either. e.g. unless it's an actual plot point, then it should be less than a 1% chance, e.g. you cut yourself shaving 3 times a year. And since it's so unlikely, it just makes more
narrative sense to prune the possibility down to 0%.