>>1347101>all vehicles on the road should follow the same rulesWhy? There's absolutely no reason for that. Cars and trucks have different physical characteristics than bikes, and are driven differently, at different speeds. It makes no sense that they be subjected to the same rules.
In the case of roundabouts, they exist to make car traffic flow smoother, without the need for a cumbersome intersection. The size is directly related to the expected flow and the turning radius of cars, which is high because velocities are expected to be high. Bikes, on the other hand, have much smaller turning radius and their flow configuration is different: there's more people, but who travel slower.
