I think you are in agreement with the parent on the overarching problem, but just bikeshedding the metaphor used to explain the problem here.

.. there is only one power company in the entire province I live in.

I understand and now you know why exactly this is bad. I for example have option to choose to buy electricity from any provider in my country and that electricity is delivered to me over wires of yet another company which handles only distribution. And that company is government ovned. If one elctricity manufacturer decides that im bad customer or gets greedy, i can swith to better supplier.

There's only one provider of power where I live.

No you can't, there is only one supplier for water and one for electricity. (Not in the US where it's privatized but that is US specific).

The lines are the same, owned by either a state or most likely a company. Unless you live in some weird place where every company installs their own lines.

I live in a place where power distribution is separated from power generation. There are multiple power producers, but they using delivery network of other companies. And thats by design to prevent power monopoly.