> I think a general principle of good governance is that the policy is agnostic to the industries which it affects and robust under any set of conditions

The trouble with this is that people frequently don't like the consequences of that.

For example, a lot of the costs of a grid connection are non-linear if not totally independent of the amount of power you use. When a tree falls on a power line and a crew has to show up and install a new pole, the cost of that has nothing to do with the average percent utilization of those wires. Likewise, a line that can deliver 100MW to a single customer costs more than one that can handle 100kW, but it doesn't cost anywhere near 1000 times as much or consume 1000 times more land etc.

The result of this is that the "works under any set of conditions" pricing for a grid connection would be a flat monthly fee for the capacity of the line totally independent of how much you use, and a line with 1000 times the capacity would only cost e.g. 10 times as much. But then a typical household electric bill would have a fixed charge of ~$100/mo for a grid connection regardless of how little electricity you use.

Likewise, if you have a high proportion of renewable generation in the grid then the price per kWh during daylight hours when there are clear skies would be essentially zero, but the price on a cold still night in winter would be oppressively high and anyone who failed to turn off their electric heat on that specific day would end up with a $5000 electric bill.

So in most places what happens instead is that the power company charges a fee per kWh which is used to pay line crews and other expenses that don't actually depend on usage and then have a much lower fixed connection charge. And charge a certain amount per kWh during days when supply is sufficient and then use the money to subsidize consumption during shortfalls, even though that actually raises total costs, because otherwise people would scream about prices hitting $500/kWh for a few hours every year or two.

But once you're doing those things, a customer that wants megawatts of power is reasonably going to object to that rate structure, because the few percent inefficiency those things induce is millions of dollars in their case. At which point people start complaining about subsidies, even though not doing those things would be the absence of subsidies.