100% efficiency is a given -- resistive heating is 100% efficient due to the first law of thermodynamics. The important cutoff is when the heat pump becomes less than 400% efficient, or when the heat pump becomes less financially efficient than a gas furnace.

Oh. I guess I don't see the need for a conspiracy to explain why two different companies charge different prices for a commodity. They have different pipeline networks, presumably different infrastructure costs, etc.

Does orange country pay less than half of San Diego? Both using the same gas provider? I'm surprised to hear that. Prices in the bay area were in the mid 40c per kWh when I lived there five years ago and folks in sf were the same. I assumed this was due to sin taxation.

Fwiw brief googling doesn't find anything to support the claim that OC is cheaper than San Diego. Con ed time of use rates are quoted state-wide here: https://www.coned.com/en/accounts-billing/your-bill/time-of-use Can you provide some source for your claim it's cheaper in OC?

It's not about the size of the pump, it's about the chemical technology used. Newer chemistries stay efficient to lower temperatures compared to older ones. Some are even efficient down below 0F.

(Conversely, a larger pump may not even help if you have a really old chemistry. Your pump would have to switch to backup resistive heat at the point where it's chemistry stops being efficient.)

Energy prices in California are high by design. It's to encourage you to make efficient decisions and use less. Same way as how even before this crisis fuel was much more expensive in Europe due to fees and taxes.