Well the holy book wonders are significant wonders and the thing is, if you don't build one of them, there's another chance to build one. And the point really isn't that they'd all be built by one civilization, although I suppose that can happen. Also, I think it'd be sort of 'wrong' to give one holy book more authority than another by making it signifanctly better. While these holy books do give off different buildings, that is mainly based on their time period, not their authority.
And thank you thank you thank you for the screenies! =D
And from the looks of things, you're either on an easy difficulty, or way too good at civ. ;D