Each time a discussion about a public service comes up, I feel obliged to remind that even if a public service is not financially viable, it may have positive externalities that it cannot capture, but that make the whole venture more-than-viable to society.
The Post Service is a classic example of such a service. They serve remote areas and communities that commercial delivery services would not cover, therefore jumpstarting commerce there. Otherwise these communities would be economically isolated and would wither away. The state usually recovers their expenses soon, given that increased commerce means increased tax income. Also, this is a form of long-term investment for the society as a whole that is non-obvious and for which other mechanisms do not exist.
The Post Service is a classic example of such a service. They serve remote areas and communities that commercial delivery services would not cover, therefore jumpstarting commerce there. Otherwise these communities would be economically isolated and would wither away. The state usually recovers their expenses soon, given that increased commerce means increased tax income. Also, this is a form of long-term investment for the society as a whole that is non-obvious and for which other mechanisms do not exist.