The U.S. Postal Service announced last week that it would continue delivering mail on Saturdays and not cut back to just parcel delivery, as it had planned.Surely, I figured, the decision not to cut the day of delivery that would save the postal service an estimated $2 billion was made in response to clamor from a public hungry for catalogues and postcards addressed TO CURRENT RESIDENT.Nope. Seventy-one percent of Americans polled by CBS News supported the cut.Perhaps the USPS discovered that the cut would not save as much money as expected, and that there was a better business approach?Nope. The official statement noted that the Postal Service's board of governors "continues to support the transition to a new national delivery schedule. Such a transition will generate approximately $2 billion in annual cost savings and is a necessary part of a larger five-year business plan to restore the Postal Service to long-term financial stability."Why the backtrack? Because cutting a day of delivery, as scheduled, would violate the will of Congress.There's a rider attached to the most recent continuing budget resolution -- isn't there always? -- mandating that service be maintained at 1983 levels. It's a strange vestigial requirement from when the USPS was a needed lifeline that now functions as a kind of appendix to the body of legislation, serving no visible purpose but occasionally flaring up and costing billions of dollars. The Atlantic Wire's piece on the subject was headlined "Congress Insists That You Get Mail on Saturdays, Like It or Not."As far as the Postal Service is concerned, Congress is about as fond of change as the Earl of Grantham from Downton Abbey, which is to say not at all, because lawmakers still think it's 1903.I'm sympathetic to the Postal Service's plight. It's in a difficult position; neither flesh nor fowl, it straggles along with too much oversight from Congress to function like a business but too much potential liability to taxpayers to be allowed to wander off. It executes, with grace, skill and reliability, a highly complex service that fewer and fewer people are willing to pay for."To restore the Postal Service to long-term financial stability, the Postal Service requires the flexibility to reduce costs and generate new revenues to close an ever widening budgetary gap," the USPS statement pleads. "It is not possible for the Postal Service to meet significant cost reduction goals without changing its delivery schedule -- any rational analysis of our current financial condition and business options leads to this conclusion."This won't get any easier. "Delaying responsible changes to the Postal Service business model only increases the potential that the Postal Service may become a burden to the American taxpayer, which is avoidable," the USPS noted. Right now, the postal service is supported by ratepayers, not taxpayers. Last year, it lost almost $16 billion between the continued drop in mail volume and the congressionally mandated need to prefund its employee retirement benefits before it becomes -- as increasingly seems inevitable -- completely insolvent.The Postal Service has a lot to struggle against. Time and technology are taking their toll. First-class mail is not returning. The labor costs of delivering through sleet and hail and dark of night are considerable. And now that people are buying homes again, the range of places to which mail must be delivered is expanding.The news that the USPS is not, in fact, ending Saturday mail delivery makes me think of an elderly man with thick spectacles, a hip plate and suspenders announcing that he has changed his mind: He is going to the club to pick up ladies, after all. Either way, we know how this ends.Alexandra Petri writes the ComPost blog for The Washington Post.