You need a towing license for anything heavier than 750kg. Europe and surroundings are like that. For any trailer heavier than 750kg, you need to pass an exam and get a license, no matter what's towing it, be it truck or car and that's the way it should be, heavy trailer behaves differently regardless what's towing it. Then again, if this would apply everywhere we wouldn't have so many funny videos of people fucking up their boats and similar. So carry on.