Now, we do live in a capitalist state and that is the prevailing ideology, but still this is weak reasoning. Justifiably, my partner has been ranting and raving this week, but has got little sympathy from her classmates, in part because it seems they haven't thought about the issue at all really. So she asked me to write up a simple argument that she might be able to modify and draw up to use in class next week when she brings up the matter. This is what I wrote up.
I'm not sure your strict distinction between ethics and morality is sustainable. You say morals are a person's private beliefs and customs, whereas you say ethics is the system of rules. But others might say morality has a religious anchor and ethics is a person's discretion to act. Do you see how these things can be easily reversed?
The reason for this is because you have made a mistake. You cannot pretend that people are isolated individuals absolutely free to decide their beliefs outside of their social circumstances. We are social creatures and we grow up in communities. So a person private conduct is informed by the prevailing system of belief, whether that be religious or cultural or otherwise.
Almost all moral philosophers say that you can study ethics like you can study mathematics. This means that there are moral facts. Think of this example: If I hurt you by telling others you are a bad teacher and so fewer people take your class and eventually you are fired, but you didn't know it was me or anyone for that mater, would your subjective ignorance of what went on mean that you weren't hurt? No, of course not.
Let's take this a step further. It is a moral fact that you can exploit someone, hurt or harm them. And this happens too often at companies. Indeed, lots of people sign up to be exploited even if they are subjectively ignorant of their exploitation, mostly because if they didn't work they would become homeless, perhaps even die. Saying that my private beliefs as HR, or the company itself, is not interested in these larger pressing questions of harm simply because the law is silent on the matter is nothing more than weaseling from, colludes with, or simply condones objective harm because they think it less important than profit. No matter how you try to define the problem away, there is nothing ethical about that.
If anyone has something to add or re-frame please jump in the comments. I am more than interested in basic clear compelling arguments.