Lol, I did well in tax class back when I took it 11 years ago, but I'm no expert. That said, I'd think Apple might be paying sales tax, but they just build it into the cost on the front end (there used to be a store here in Seattle called "Always No Tax!" and that's what they did.)
Amazon's maneuver today was meant to avoid having to collect tax in their main lines of business (which includes Kindle) in California. Amazon is reducing their contacts in the state so that California won't have jurisdiction over them so that the state could require that Amazon collect sales tax. That's good news for your kindle book purchases, but not so good for a state that's having huge money troubles. Of course, for you to fully comply with the law, you should report those purchases to the state and pay the state of California the tax that you owe (lol like that'll happen.)
Theoretically, the state could come after you for those amounts owed, but the juice wouldn't be worth the squeeze. Way too much work for them to make it worthwhile. That said, I have heard of states tracking big ticket purchases (like art) and going after the purchasers.