It’s not really about the dollar amounts. It’s the fact that my employer is using an information asymmetry to arbitrage my labor.
Here’s an analogy. Say I wait tables at a restaurant. If I discover my boss has been skimming off my tips, I’m going to be upset — even if I was perfectly happy with my pay before I learned that.
That's not really germane to the discussion though. The only reason you can be sued or charged for skimming tips is that we decided to make a law against it. It has nothing to do with whether they're comparable in a moral sense.
Here’s an analogy. Say I wait tables at a restaurant. If I discover my boss has been skimming off my tips, I’m going to be upset — even if I was perfectly happy with my pay before I learned that.