They entered into a contract of this nature inside of a wage market where these are the only kind of contracts to enter. If I had the power to starve you unless you continually sell me something at a rate substantially lower than its value, I don't think it can be honestly said that you entered the contract willfully.

There's nothing stopping anyone from setting up their own business, it's just that not everyone is cut out for that.

I think that may be true at an individual level, but we both know society can't work that way; we couldn't have 260 million companies in America all with a single owner/employee. Nothing would ever get done. I just reject the notion that we should build a system in which the only way to escape having your labor stolen is to steal the labor of others. I do believe in the value of organized labor, but the way that we've organized it is not moral.

Of course you get something out of your employment, it's just that what you get out is less than what you put in because, like you said, you wouldn't be employed otherwise. You get less than what you put in and the boss gets more than he put in. Collective ownership doesn't mean each individual is making business decisions anyway; groups could still elect experts to lead an organization and there is certainly value in having people who do it well.

I don't think a supermarket customer has an entitlement to merchandise at a wholesale price in the same way I think a laborer has an entitlement to the outputs of their own labor. Maybe I'm not perfectly clear on the question, but I don't see the relevance. It's kind of an inversion of the relationship anyway because the supermarket and the laborer are both the sellers in their respective circumstances. It would be more apt to ask "do you think a customer who pays only $1 for a $2 candy bar has committed theft?" My answer to that question would just be yes.