Which actually makes sense, if you have a high upfront cost, constant output source iike nuclear, taxing each individual unit makes no sense since the marginal cost is effectively zero up till you need to build a new plant. Whereas if you burn coal or gas, you want to incentivise people to cut back for cost, carbon and pollution reasons.

An even more sensible approach would be to tax the carbon directly and charge more for peak electricity since that contributes more to the infrastructure requirements, which I guess both countries will already be moving towards as is the current trend in most places.