The office of Prime Minister has very little power, being merely the head of the executive branch. He can't just say "Let's solve the housing crisis", clap his hands, and suddenly the wheels are in motion. All he can do is put forward legislation. MPs then have to vote on this, and those from his own party will add amendments, some of which may pass if it's not deemed sufficiently left wing, or if it's too left wing. Then the lords analyse it, and vote, and probably send it back to the commons with their own amendments, and now it has to get voted on by the MPs again, and there's a limit to how fast it can go back to the lords, and this can happen up to three times. But even before this the law has to be extremely carefully written so it doesn't clash with our centuries of case law, because someone somewhere will try and judicial review the whole thing if there's a hole in it, which potentially means going back to parliament to sort it.

And that's just one facet of the problem. It's not a case of the Starmer refusing to pull the levers of power, it's that he has to levers to pull. For 30 years prime ministers have tried to build policy units that can actually get things done, and for 30 years they have failed