NPCs are stronger than the enemies you face. Hit an enemy with a bullet, drop a grenade near one, and the pussies die right there. Do the same to an NPC, and they'll yell at you about watching what you're doing as they walk off without a scratch.
Somehow the little belt you have on can hold multiple guns, swords, shields, health potions, staffs, crossbows and such, all at the same time... yet your ass isn't encumbered by any of it.
If I ever get into a horrific car crash, somewhere, somehow, there will be several high-speed cameras around to capture the ensuing cascade of flying metal, sparks and body parts from multiple angles in crystal-clear slow motion.
Marines in the distant future will be made up of incredibly fat men and women when they finally journey into space. That's the only logical reason for why they won't be able to step over foot-high walls.