That's fine if you just want to learn University Physics on your own, but in college the professor will usually assign homework from problems in the book, which a comparable book won't have.
While that is true I think you're missing the point of my argument. If I'm learning for the sake of learning I don't care whether the professor assigns an assignment out of one book or another. I, as a non-student, have an interest in a subject and I am now able to buy an equivalent High School, College, or University Textbook to learn from for 15 bucks. I don't have to spend hundreds of dollars, I can now spend fifteen, and if I decide I like it enough to attain formal education in the subject, I might even be able to take a placement exam that would give me credit for the self taught material I've already covered.
Also, for K-12, although the thought of being able to buy books for $15 sounds great I think the start-up/maint costs will be too much. Hardware will increase every year, and hardware requirements for software will increase to match that.
Its cheaper than you think, if you think it through. Think of the average Grade 9 student: Math, General Science, Chemistry, English, General Computing, General History, Geography.
They'll need text books for all those classes, sometimes more than one if multiple topics are covered during the year. Lets assume they only need one for each for a minimum of seven textbooks and estimate a hundred bucks a pop, now they're going to need to buy textbooks for each year that student is there. Lets assume the same number of textbooks each year for the student's four year run: 7 x 100 = 700 x 4 = $2,800.00 per student per four year period.
Most schools replace their textbooks every four - five years, so basically once a student graduates they replace their entire textbook roster for all classes all at once.
Or they can spend $599.00 on a 32 GB iPad, lets get the mid line model in case the textbook authors decide to go a bit crazy with the video, and give the student 28 redemption codes for their textbooks over the four years which tacks on an additional $420.00. All told the district would spend $1,019.00 per student per four year period. And we haven't even covered off on any education discounts Apple would include in selling them an iPad, which there probably would be since Apple usually does provide the hardware at education discounts.
With proper care the iPad would certainly last for four years and as an incentive to treat it well, and solve the updated hardware problem, we could let the student keep it when they graduate; what an incentive to the student, do well in school and keep your iPad for College / University. Sure it would cost a fair bit to get the program started but once its running the cost in new hardware would be limited to the freshman class size each year and you wouldn't have to worry about disposing of obsolete hardware since the student's would be taking it with them.
As for insurance premiums use some of the savings for Apple Care, that should cover most stuff, and then set aside a bit more for breakage. Most schools already do something similar with their paper textbooks anyway by purchasing a number of extra copies allowing them to replace excessively damaged ones as needed.
In relation to IT costs, its an iPad and not a general purpose computer. It therefore wouldn't need the same level of IT support as a general computer would, a bunch of Wi-Fi nodes and a copy of iCloud set up for the school to coordinate textbook and lesson plan distribution should cover that. Hell that sounds like it'd be fun to set something like that up, I wonder what it takes to become an Apple Certified Technician.