If the metric is important (and it might well be! -- I bet it is) it needs not translate into more profit for amazon.
Say you want to maximize efficiency, and you think revenue per worker is a good proxy. Then you can use the extra resources for:
* charitable donations
* keeping the employees and putting them in an open-source charitable division
I agree that market forces are powerful and can be used to do good things. I disagree that this fact should be used to justify evil behavior and greed
(also, laying A off and hiring B is ok -- they are not, they are reducing the workforce)
(also, the argument is symmetrical. If they had not hired, and were profiting too much, I'd think that almost as greedy and evil -- the difference is the disruption of the life of the person fired)
(also, firing A and giving the money away to some charitable cause is ok)
(also, profit maximization pure and simple is ok, as long as the government has the balls to take a lot of it and redistribute, to keep capitalists from concentrating too much money -- concentration leads to distortions, in the sense that the needs of the ultra rich are prioritized. The point of having a healthy economy is to have people in general live more and better lives.)