> every government since the mid-2010s has been elected on the explicit promise to build more houses, they cannot do so because of the electoral consequences

This doesn’t add up. Promising to get more housing built is getting these people elected, but they can’t make good on this promise because then they will lose their election?

It depends what you mean by add up. Logical? No. Reality? Yes.

Politicians continue with the lie that they will build council houses. Voters continue with the lie that voting will change the outcome.