Ratios between the top and the bottom

Professor Herman Daly points out the military, civil service, and universities manage to keep ratios between the top and he bottom salaries in their organizations within a range of 15/20 to 1 and seem to do okay with no lack of highly skilled, motivated, and competent leaders, yet the corporate spread in the United States is now up to 500 to 1. There appears to be no evidence that such ratios actually encourage performance across the economy.