I believe Apple does do this - it's $99/year to become an Apple Developer, and I think you need to be an Apple Developer to have an app in the app store.
It is $99/year to have apps in the App Store, but it is per developer account and not per app.
I almost think devs would be better off if it was per app. At least any devs planning to make a living off the store. It would cut down on a lot of the crappy spammy apps out there.
It would also kill the one-off hobby stuff with which many, especially teens, get their taste for (app) development, which would be a high price to pay. Without a secondary path to distribute apps I think it would be a bad idea.
