The real reason is Congress imposed a crushing mandate on the Postal Service back in 2006, requiring it to prefund decades of future health care premiums for retired postal employees in advance. This prefunding mandate, which no other enterprise in the country faces, cost an average of $5.4 billion annually since 2007, accounting for nearly 90% of the agency’s losses. Between 2013 and 2018 it accounted for 100% of the losses.