Because a drone is a lot smaller and thus constitutes a heavily reduced risk.
> Imagine remote controlled cars on the road. Should we allow some drunk kids without license on their computer at home to control cars on the road (and endanger everyone else), just because they are not in danger? Of course not.
So, to borrow your imagery here: A bicycle is a lot less risky to traffic and people than a car is and thus you are allow to drive it without a license and punishments for violations are in general lower than for cars.