Character Sliding Animation Collision?

How is the collision solved in games when you are crouching, laying, sliding etc…?
Is it only this awful in unreal engine?

Simple meshes like boxes or more complex objects or even a whole HOUSE can use complex collision as simple which creates a collision around the given mesh EXACTLY where it needs to be covering the entire object/mesh insanely precisely.

While for characters we have sphere and capsule colliders, REALLY? Why cant we generate a precise collision around our character?

I want to do a simple sliding animation, and setting the capsule half height to go through objects while sliding makes the camera jump up and down (because I have to place the character’ Z up and down when the capsule’ height changes).

Is there any better solution for this? Is there or will be there a solution that creates a precise collision around the character mesh, and when the character does an animation, it follows the mesh? It would be insanely simple, why is it not possible?