I understand you believe this, but can you explain this discrepancy between the water heaters? I figure by the least efficient electric heater you mean a resist

I understand you believe this, but can you explain this discrepancy between the water heaters? I figure by the least efficient electric heater you mean a resistive one, so it's close to 100% efficiency, right? There are plenty 90% and 95% AFUE gas heaters on the market, let's say 90% is the most efficient so it should be using 1.1x more energy than a 100% efficient resistive heater but in your numbers the gas heater uses 1.33x more energy. I.e. you claim the most efficient gas heater is 75% AFUE? I don't think these are even legal to sell in the US any more.