Surely this is because utilities don't separate the costs of the infrastructure from the cost of the energy. In market based systems like Norway we pay for three distinct items: the energy, the fixed costs of the infrastructure, the cost of transporting the energy (the losses in the infrastructure). So I pay the first item to one company and the second and third to the local company that owns an maintains the infrastructure. The infrastructure owning company will still charge me for the cost of maintaining the infrastructure regardless of how much energy I buy from the energy supplier.