In France the CNIL is pretty good at enforcing regulation IIRC. And for any small to medium company, the fine should be enough of a deterrent.

I don't think companies big enough to just shrug the fine away resort to much telemarketing here.

This law is especially targeted at legit businesses... It's already illegal for scammers to call.

And I don't think something being hard to enforce is reason enough to not do anything about it. If we truly care about something, we can always find a way.