Why can't people be allowed to retire at 55 years of age?

Anyone can retire at any age they wish. If you can afford to retire, self-sustained, at 55 (or even 35 if you want) then do so. But, if you are going to retire and depend on social security or state pensions then you have to work well into your sixties. We can't afford to pay people retirement benefits for 25 or thirty years after they retire. That was not the intent of subsidized retirement.