I think it's just capitalism, and economics.

Consumers are constantly pushing down the prices on everything, expecting more and more for less and less. Faced with this reality, companies have to streamline and become more effective in order to succeed and profit. This is what Amazon are doing.

We moan about having to pay for baggage, choosing seats, food and even using the bathroom on flights now - but this is solely because of our want to push down the headline price of flights. The price has been reduced...but the cost is still there.

AFAIK, Amazon aren't doing any illegal, they're just working very efficiently.