have some kind of (moral?) restraint that prevents them from draining companies dry of profit.

That they won't stand in the way of technical innovation.

That they won't ossify job descriptions to the point of impairing flexibility.

Unions stand for only one side of the problem, the workers - thier actions will necessarily tend toward that extreme REGARDLESS of how well the employees may be treated by mgt. After all, don't people always want more, over time? They need balance; I think competition could provide that balance.