For high schools, the main cost in production is lobbying the state standards board. For colleges, buying decisions are made by people (professors) who don't have to actually spend the money. There's no advantage to undercutting someone on price.
I don't know. I'm a lot more sure that those are the reasons that nobody's created a bunch of open source textbooks than I am that Apple can somehow break through. I guess there's a chance that the Apple aura is enough of a draw to break through the established system?
