To be fair, the USPS is only "losing billions" on retirement funding due to the pre-funding obligations imposed by Section 8909a of the Postal Accountability and Enhancement Act of 2006, not obligations owed to current employees or retirees. [0]
There was some speculation at the time that this was a regulatory attempt to "tie their hands" on investments to address the online shopping market, which has more than offset the decline in carriage due to email. For example, during the 10 year period covered by the pre-funding obligation, UPS managed to increase revenues on domestic shipping by ~45%. [1]
Excluding these mandatory payments, the USPS is actually slightly profitable, to the tune of (conservatively) $92M as of 2015 [2]. In this context, a $79M loss is a major portion of their annual profits, although still a drop in the bucket compared to their gross revenue.
There was some speculation at the time that this was a regulatory attempt to "tie their hands" on investments to address the online shopping market, which has more than offset the decline in carriage due to email. For example, during the 10 year period covered by the pre-funding obligation, UPS managed to increase revenues on domestic shipping by ~45%. [1]
Excluding these mandatory payments, the USPS is actually slightly profitable, to the tune of (conservatively) $92M as of 2015 [2]. In this context, a $79M loss is a major portion of their annual profits, although still a drop in the bucket compared to their gross revenue.
[0]: https://www.govtrack.us/congress/bills/109/hr6407/text
[1]: http://www.investors.ups.com/phoenix.zhtml?c=62900&p=irol-re...
[2]: https://about.usps.com/who-we-are/financials/annual-reports/...