You are still thinking "inside the (British planning) box".
The huge price differential between land with and without planning in Britain is a consequence of our ultra-restrictive planning system. If our planning system were mainly normative as opposed to mainly restrictive, then the current price gap - the planning gain - would not exist, or be much smaller. Do you agree?
And if you change fast to a more liberal system, and announce it clearly beforehand, you also reduce the initial "residual" planning gain.
But the most important issue is to reduce the cost of building land as much as possible, and to revert this housing cost inflation.
If you are insinuating that I own land, no, I don't. I would like to buy a building plot but I can't afford the planning gain. I could afford a fairly priced plot, and the building costs, but not the huge planing gain premium.
And what about you? Why do you systematically opposes planning liberalisation? Don't you own a house already? Why do oppose new house for others?? It's weird. And IMHO, it's not fair. Think about it.