Okay, the article from Groklaw (via Clay Shirky) The Stupidest Lawsuit Since the World Began is over 3 years old, but I didn’t see it before, and I don’t know how it resolved …

The women, who live in Moselle and work five days a week at European Union offices in Luxembourg, are being sued by Transports Schiocchet Excursions, which runs a service along the route. It wants the women fined and their cars confiscated.
Two years ago a business tribunal threw out the company’s case. It is now pursuing the women in a higher court, saying their action has cost it €2 million ($3.2 million).
The women explained that for many years cleaners used the company line for the 40-minute ride across the border, which cost them €110 a month.
“Using our cars is quicker and at least twice as cheap. And on the bus we didn’t have the right to eat or even to speak,” said Martine Bourguignon.

Yes, they were sued for carpooling rather than paying to ride the bus.
While absurd, it is not so absurd as to be unknown.
Bus monopolies in the US generally prohibit competitive for hire jitney and shared taxi services, as well as competing bus routes. See Curb Rights by Daniel Klein, Adrian Moore, and Binyam Reja for further discussion.