So in France, GPL violations are not considered a copyright issue, they're considered a breach of contract. And since the court looks at the damage to the victim in breach of contract cases, which is hard to realistically imagine when the software is given away for free, this is some bad news indeed. Someone uses your GPL code, gets caught, pays a minimal amount in damages, and continues using it.
One of the strengths of the GPL is that companies don't like it for some reason. Since they don't like it, you can offer to sell them different licensing terms. That is what the damages are. It's not $0, it's all the money you missed out on from not being able to license your project.
> So in France, GPL violations are not considered a copyright issue, they're considered a breach of contract.
They are breach of contract in probably any country, but due to a automatic termination clause the breach of contract immediately leads to a copyright violation as you no-longer have usage rights as they where terminated.
So it's always a breach of contract but in the US that breach of contract triggers a copyright violation where in France in that specific case it did not.
> to realistically imagine when the software is given away for free, this is some bad news indeed.
The software is free under certain terms, so you would need to find a realistic price for software without such terms. Which might be hard for a small ad-hoc library, but should be very doable for any larger software project.
> , and continues using it.
This wouldn't work they would pay some amount of damages (see above) for their usage until then, but you also can terminate their contract and in turn they would need to stop using it or (as far as I understand) they then (and not before) could be sued for copyright violation.
I'm not a lawyer and stuff.