As far as I understand it, the UK housing market suffers from an additional problem that is rare to non-existent in the US: builders who get planning permission

As far as I understand it, the UK housing market suffers from an additional problem that is rare to non-existent in the US: builders who get planning permission for new housing but then sit on the land because they know with almost 100% certainty that built or not, it will be worth more in the future. There are places in the USA where a builder could take this bet, but it would be much, much riskier.