A private monopoly on its absolute worst day would still operate more efficiently than a federal or state power agency. One still has a bottom line, the other just has meetings to look busy.
Not really. A dysfunctional private monopoly will go as bad as they can go without having people just abandon a product/service category entirely. Which, in case of captive audience or a necessity, can be really bad. Oh, and with falling quality prices can still go up - it's a monopoly, after all, it's not like customers can go elsewhere.