After World War II, ridership on the ferries that transported workers in Seattle’s shipyards fell off. So the state of Washington took over the business of running Puget Sound’s ferries.

The reason some wanted the takeover of the ferries is that they didn’t want to pay increased fees. But the takeover didn’t magically make the costs go down. Instead, the state — that is, taxpayers — covered the losses.

Now Washingtonians learn that their system has a different kind of a ticket problem. Some of the millions earned from sales may be missing.The amount? Well, in the words of state auditor Brian Sonntag, “it might be zero.”

But it might be a whole shipyard more than that. “The ferries department cannot identify if any is missing,” Sonntag said. The problem isn’t new, either. This is actually the 21st year the ferry system has confessed to not knowing where its money went.

This is one of the problems of state-run businesses. They are protected from competition. The workers and managers know that the budget shortfalls will be met by the government. So they tend to be a little lax about matters like, uh, accounting.

I’m not saying this kind of thing doesn’t happen in private business. We all know horror stories. But when this happens, heads tend to roll. Businesses go out of business, and new ones emerge to take their place.

The trouble with state ferries is, well, the same as their advantage: there’s no end in sight.

This is Common Sense. I’m Paul Jacob.