Why must heavy commercial vehicles yield extra room to pedestrians and cyclists when executing left or right turns at urban junctions?

1. Truck off-tracking, blind spots, and wind turbulence create severe collision and crushing hazards along the side of the turning vehicle
2. Pedestrians can always see the truck, so responsibility for avoiding it rests with them
3. A cyclist alongside the cab stays visible in the mirrors throughout the turn
4. The trailer follows exactly the same path as the cab, so the kerb line stays clear