It is hard to know for sure Bob. It is not taxes (because why would that only affect residential customers?). My bet would be on lack of competition and gaming of the pricing mechanism by a limited number of generation suppliers. Residential buyers have the least market power so they are the ones carrying the can. The government is a major shareholder in the electricity companies, profits/dividends are high, which they are probably not unhappy about. So they might not be thinking too hard about how the market could be better configured.

Fundamentally the increases in retail electricity prices reflects the averaging over the medium term of marginal prices (wholesale spot prices). Going forward, the more high demand/low supply events =the more thermal generation is used =higher prices. The beauty of being able to store energy cheaply with the likes of pumped hydro is low cost but intermittent supply -like wind becomes viable to replace thermal.