I'm failing to see why any of this is immoral. Taking every (legal, nonviolent) advantage is called "doing business". We live in a competitive ecosystem. Under such conditions certain behaviours are emergent from the system. It creates the niches that make this behaviour optimal. If you don't want to be taken advantage of by a sharp, don't be a square.
I don't see how living in an ecosystem, complete with selective pressure, asymmetrical compounding advantage, etc. can possibly be immoral, since it's fundamentally inescapable.
You seem like the type of person that will take advantage of others when a loophole law permits it. Sure, it may be legal, but it still makes you a bad person in my book.
Like most people, I treat people I know with a lot more kindness than people I don't. Whether most of us like to admit it or not, our actions demonstrate that we don't generally have much regard for distant strangers, no matter how profoundly they suffer and how much we benefit from it (see the conditions in which most of our goods are made). You can call that immoral, but rational self interest is absolutely normal human behaviour, and I'm not even a psychopath.
My point is that the niches exist to be exploited by the least scrupulous among us. As long as the niches exist, they will be exploited. Resenting that is akin to resenting the biggest fish in the pond for being so damn aggressive - it's pointless. We live in a pond, and we should focus on maintaining the nonviolent and often ecosystem-benefitting nature of the exploitation (since it is hard-won and precarious), rather than resent the inescapable reality of its existence.
I don't see how living in an ecosystem, complete with selective pressure, asymmetrical compounding advantage, etc. can possibly be immoral, since it's fundamentally inescapable.