Services which operate for the public good can operate at a loss if government-run or regulated and subsidized. Many police departments run at a "loss", in that they effectively bring in no money aside from a few donations and run almost entirely off government treasuries, but it does not follow that they should be eliminated!

Monetary gain or loss is not the only way to measure whether a particular function is overall good for society. If a particular function provides a great social good but little opportunity to make money (or massive opportunity to take advantage of a chokehold), it is a natural for public ownership.