I wouldn't be too surprised if they simply hire armies of reviewers that simply work through a checklist with limited room for interpretation/personal evaluation.

I a way, they could just publish their internal checklist to make this process better for everyone, but I suspect it might cause bad actors to find ways to comply with the rules and still deliver crap to the store; almost like the rules they currently use are security by obscurity (with the side-effect of rejecting apps for seemingly random reasons).