And the owner has to have at least a reasonable chance of getting paid back for their investment. They're not building a steel mill as a charity. So if you don't let the owners make money off of their steel mills, then you don't get any steel mills. Whose life does that make better?
[Edit: And letting the owner make as much as the janitor isn't going to cut it. The owner is putting in hundreds of millions of dollars; letting them get back $15/hour is a completely inadequate return for the level of risk they are taking.]
But if they did, they'd still be investors (i.e., employee-owners) and everything I said would still apply :).
More seriously, employee-owned businesses aren't uncommon, but still, the investors/employees are profiting from the company's increased producitivity _as investors_--their wages don't increase, the value of their shares increases. Just like owners in sole-proprieter businesses like our hypothetical steel mill.
No one said they built it, just that they owned it. It's totally possible (and common!) to own something that you didn't build and have never had a hand in operating.
But lets say a new steel plant was built. Who actually built it? Was it the the owner, or the project managers, engineers, architects, construction crews, etc.? Which of these groups contributed more value to the enterprise?