McDonalds COULD sue anybody and everybody who uses their IP. But they don't due to not knowing about it, to put it simply, like T4VERTS said. Then it all comes down to whether you (company whose rights are being infringed upon) think it's worthwhile or not. Think of it like these tattoo in video games cases. For the artist it's worthwhile because they probably aren't raking in the dough everyday. So a couple hundred thousand dollars is worthwhile to them. But for McDonalds a 2.666 billion dollar company is it worthwhile for them to waste months or years in court to gain an extra 200K or what the damage payout would be?