Driving a car for hire (like Uber) is also illegal without a taxi license... At least in The Netherlands. Doesn't mean people don't do it.
And you could always rent a plane without a pilot, then ask a friend with a pilots license to fly it for you for free. He doesn't get paid to fly the plane, so that would be fine. Now you need to find an aircraft owner who would rent you the plane while you don't have a license. Maybe a friend of you would do that, so that would be OK too. But what if that pilot friend is the same person as the aircraft owner friend? Gray area...