Why is this an incomplete picture? Because one must imagine a hundred, or a thousand, or ten thousand of these machines all chained together. Each operator cranks away at the machine earning a penny almost every 5 seconds. What you don't see is that as the operator cranks away, each machine is also spitting out a penny every so often, which is funneled into one bucket not shown. That bucket fills up a lot faster than the pocket of the operator at the crank. While the penny machine above has not gotten any faster, the speed of the pennies going into the big bucket has gotten much faster over time.
It is not that the minimum wage is low, but that minimum wage workers create vast wealth. We all snicker at someone like Paris Hilton, a young woman who doesn't work, but is ridiculously wealthy. Her wealth comes, in part, from minimum wage workers, cranking out a penny every five seconds.