@Shadowman311 They are probably using a human maker solution like Metahuman to make their citizens.
3 problems with that:
a - these softwares are for highly detail humanoids so simplification of the end characters are responsibility of the developer.
b - they are using Unity3D, that does not have automatic LOD generation, so de developer have to create lower detail models.
c - these models normally use full skinned meshes, these are meshes for skeletal animation, so every frame of animation each vertex have to interpolate between the frames based on the bones, so the developer have to separate simple meshes from skinned meshes for optimization.

Basically is modern developers don't understand that not everything is automatic, they actually have to understand the technology and optimize for it.
That's why i fucking hate Unreal and Nanite, every faggot the jizz over nanite without having a clue of what it is other than "infinite detail" needs the rope.