Some journals do offer compensation - I think the American Economic Review used to offer £100. The solution hasn't been widely adopted, though, perhaps because academics enjoy the kudos of being a reviewer (and the chance to savage other people's work anonymously :-P... ). And while you can pay for reviews, it is hard to pay for review quality, which is very subjective.
Also because a price that would significantly incentivise a
senior academic is a price that is way too high for most journals to pay. If you have prestige, a decent if not exorbitant salary, bulletproof job security, a project you're passionate about and want to spend time on, and way too many obligations to actually spend time on your project, how much would you take in exchange for adding yet another obligation to the pile, taking time away from what you really want to spend your time doing?
