Why are retirees expected to have such high incomes? I fail to see why 50% or less of their incomes isn't enough. Not trying to be difficult, it just doesn't

Why are retirees expected to have such high incomes? I fail to see why 50% or less of their incomes isn't enough. Not trying to be difficult, it just doesn't match my blue collar parents' experiences. Most peoples' expenses in retirement basically amount to either property taxes or rent, healthcare, and food. And Medicare kicks in at 65, Social Security around the same time.