As the USPS is a quasi-government agency, they get their own laws.

There are standards in private industry, but not much teeth to oblige companies to comply. The insurance fund that was set up by the Federal government for corporations with defined benefit plans is in trouble. Corporations fail and the plan gets turned over for the insurance company to administrate and fund, premiums to be paid by the viable corporations have not kept pace. The reason I have referenced this is my old employer wanted to buy out my pension, due to the current formula it was in their best interest to do so as the math worked to offer a modest sum. I declined of course. Then I got a letter that as of 1/1/2015 there will be no more participants, any new hires or rehires will not be eligible. Perfectly allowable. I expect in the next 30 months that they will kill off the pension entirely, buy annuities to cover the obligations, and since the pension fund at this point is overfunded, if that holds they will get to pocket the remainder back into the corporation's general fund, what any good CFO would advocate. As the companies that compete against them no longer offer pensions for the most part due to bankruptcy it is no longer an expected benefit. We live in interesting times.