Not just that, but you can buy an iphone in an apple store directly or on amazon, in a walmart, or whatever local tech store is near you.
So to be clear: if Apple printed on every iPhone box, "This phone is 30% cheaper on Apple.com", you feel that Amazon, Walmart, Best Buy, %LOCAL_TECH_STORE%, etc. should be legally obligated to stock those iPhones?
A better question is, why aren't iphones cheaper at apple stores?