The law says it's forbidden to sell something at a loss. While it's straightforward to evaluate when you resell a physical good as-is, it's quite more shady when you do some transformation (maybe at least the sum of its components?) and outright undefinable for intangible goods, let alone a service. That's the letter of the law, but the spirit of the law is to prevent undercutting your competitors to death.
I bet all of this is tied to IGN (France's national mapping agency) offering GéoPortail, a free but absolutely crappy service and a paid yet just as crappy service and dying a horrible, deserved death. They should have kept doing what they do right: providing map data and securing a deal with Google or Nokia for the aerial and street shots, and the maps.