£9bn due to not having built more cheap onshore wind, £5bn due to poorly insulated homes, £5bn due to low solar deployment, £3bn because new homes were built less efficient.
Houses that can’t be further insulated simply need a bigger pump and larger radiators to make it work. No need for 70 degree flow temps at all, though 50 is easily achievable. With the government grant Octopus are currently charging not much more than a gas install.
I’m not saying it can’t be done. But a larger heat pump and replacing all radiators drives up the cost, there is not always space for a bigger radiator, (and water tank), and while higher flow temperatures are possible, it tend to reduce efficiency. Sometimes it’s just not worth the investment, not helped by the big gap between gas and electricity prices in the UK
Your initial comment was that the average UK house isn’t suitable for heat pumps. This is incorrect, in the vast majority of UK homes (including the poorly insulated) they can be heated sufficiently by a heat pump.
Don’t spread misinformation. Some installers have fixed prices regardless of the number and size of radiators. There’s even solutions out there where a hot water tank can be fitted into a standard kitchen cupboard.
You keep mentioning high temperature units which are less efficient, they are only needed in very niche installs or used by poorly trained installers.
