Apple and Google should update their policies where they take a much smaller cut if the user got to the App Store page directly (via external link) or a direct search. They deserve the 30% cut if users find the app by browsing the store (which doesn't happen nearly as often).
Maybe intel deserves 30% of the cut since you used their CPU to find an app when you use a web browser. How about Firefox, do they deserve a cut? Maybe Comcast since you used their network. Apple & Google don't deserve 30%, their app store is a monopoly. The same way it's unfair for Microsoft to force you to only use Internet explorer is the same way it's unfair for us to be forced to use the app store. There should be other alternatives, and none of them should have a restriction such as, "You can't publish your apps with us if you do with another store".
