By passing laws forbidding "mandatory retirement," the government reduced the number of older people who would otherwise have retired and begun drawing Social Security pensions. This self-serving transfer of billions of dollars in financial liabilities from the government to private employers was thus presented as a virtuous rescue of older workers from unfair discrimination.
Never mind that the Constitution forbids the government from changing the terms of private contracts. Never mind that younger workers find their upward path blocked by older workers whom the employer cannot get rid of without legal hassles.
All of this is washed down with lofty rhetoric about how age need not mean a decline in efficiency, about how our senior citizens still have much to contribute, about how older Americans are "breaking the silver ceiling," in the words of Senator John Breaux at recent Senate hearings.
In other words, the assumption is that individual employers looking directly at individual workers, whose work they are already familiar with, are not smart enough to make as good a judgment as distant politicians talking in generalities.
Even in the past, when a particular employer's obligation to employ workers expired at a certain age, there was nothing to prevent a mutual agreement for particular workers to continue working when the employer saw that the particular worker's productivity made this advisable and the worker wanted to continue on.
In short, neither Senate hearings nor "expert" witnesses were necessary. Much of this is a charade to allow the government to raise or eliminate remaining retirement ages, in order to escape from the impossible situation that politicians created when they designed Social Security as a pyramid scheme.