Notice how rarely anyone is argued out of the deadline, and how often they are simply moved past it by a change in circumstance. The mind that evolved for small groups and immediate dangers is now asked to manage a pension. It does its best. The strange thing about the deadline is not that it exists but that it works, most of the time, for most people. Institutions know all this, of course, which is why the deadline is so rarely left to chance.
A better question
If you want to see fairness at work, watch a queue form where there is no reason for one. The lesson is modest. Build for the person who exists, not the one in the model. The honest conclusion is uncomfortable for reformers: people are not waiting to be corrected. The strange thing about the deadline is not that it exists but that it works, most of the time, for most people.
