Can't give the AI financial bonuses, it would be impossible to get started. It's difficult as it is, with the AI being programmed to destroy the player at all cost and not accept peace ever, but you can handle it because once you destroy their army they can't make another for a while... but neither can you, you're as bankrupt as they are for quite a while.

If they got bonuses then they could just pump out army after army while you are a sitting duck.