A couple of points.
This doesn't apply in all countries. In UK for instance, it is common to have a standing charge (flat fee per day) as well as a usage charge (fee per kWh). Or some utilities charge a high price for the first few kWh, and then a lower price for subsequent kWh, which has a similar effect. See here for some details.
Even where there is a single price (a price per kWh) it is not true that the "correct" market price is just the marginal cost. Suppliers do need to recover their costs of capital, and fixed costs, or they will go out of business. Imagine a market with a huge numbers of suppliers, where the price drops to marginal cost. They will all be losing money, but some will go broke quicker than others. As suppliers exit the market, the remaining suppliers find they can increase their price, and equilibrium is established when some marginal supplier is just hanging on in the market (barely making enough revenue to cover total costs). If the number of suppliers drops below this equilibrium, then they all start making large profits, but this situation should attract a new entrant into the market, so restoring equilibrium. That's how the market theory works of course: real life situations create both barriers to entry (overregulation, obstruction of access to wholesale supplies, or to the distribution network) and barriers to exit (loss-making firms are propped up for years by subsidies, bailouts etc).
This doesn't apply in all countries. In UK for instance, it is common to have a standing charge (flat fee per day) as well as a usage charge (fee per kWh). Or some utilities charge a high price for the first few kWh, and then a lower price for subsequent kWh, which has a similar effect. See here for some details.
My perspective is US-centric, but from what I'm aware the per kWh price in most countries for most people is well above the marginal costs. Many places do have a daily or monthly charge but that tends to be $10 or less--not even close to high en...
Example nicked from this online Berkeley lecture.
Monopolies are bad (morality and economics agree here).
Firms that pollute are bad (morality and economics agree here).
What about monopolies that pollute?
What about strong monopolies that pollute and receive government subsidies?
Well...
Pollution, and other negative externalities, cause firms to produce too much of their product. That's because they don't pay the full cost of the product, including the impact of pollution.
The equilibrium behaviour for monopolies is to produce too little of their product, to keep prices and profits high.
So a monopoly that pollutes is subject to two opposite tendencies: the unpriced-pollution tendency to produce too much, and the monopolistic tendency to produce too little. If the effects are of comparable magnitude, then the monopoly might be much closer to social optimum than a free market would be (the social optimum, incidentally, will generally involve some pollution: we need to accept some pollution in the production of fertiliser, for instance, in order to have enough food to stop people starving).
In fact, if the monopolistic effect is too strong, then the firm may under-produce, even taken the pollution effect into account. In that case, we can approach closer to the social optimum by... subsidising the polluting monopoly to produce more!!
And that, my friends, is why economics is not a morality tale.