That has always mystified me as well. What, besides corruption of some kind, could possibly explain it?
After about 30 or 40 years of watching it and knowing that people were spending their entire working lives living off of it until retirement, and then it turning into a multi-generational time span, I started thinking of the mystical.
I was born into the building of the I-45 freeway to Galveston, would my life end when the construction ended?