Your examples break federal law; I'm exploiting Amazon's proprietary codebase to lower my prices / someone is still breaking and entering into my home. Those aren't moral because federal laws are being broken.
If Amazon charged $20 for a book if I were to buy it on my laptop, but $10 for that same book if I buy it with my phone, why in the hell would I buy it on my laptop? How is that immoral? I'm presented with two options: $10 or $20 for the same item. The company has offered me a contract of payment and I am to choose one, or I can take my patronage elsewhere. This is not a matter of breaking into a server and SQLi'ing until you can make an item free; this is the company offering me something for cheaper, depending on how I buy it.
If Amazon charged $20 for a book if I were to buy it on my laptop, but $10 for that same book if I buy it with my phone, why in the hell would I buy it on my laptop? How is that immoral? I'm presented with two options: $10 or $20 for the same item. The company has offered me a contract of payment and I am to choose one, or I can take my patronage elsewhere. This is not a matter of breaking into a server and SQLi'ing until you can make an item free; this is the company offering me something for cheaper, depending on how I buy it.