I think the area where Trump has been most foolish and shortsighted has been in alienating allies in international relations. He likes to throw his weight around and make like he has no need of allies, but the fact is that nations, even the US, will need international relationships. And he has done this for really no good reason, he could easily have kept things more civil.
So now he is struggling to find friends when he needs them, and it's his own fault. And it's very appealing when your leader stands up to someone who acts that way - Justin Trudeau, my PM, ran with that to bolster his popularity for a few years with some success.
However, that doesn't mean that refusing the Americans is pragmatically the best idea. Not just in terms of what they might do - it does not mean that what they are asking is wrong.
I think that Starmer may have made the wrong choice here, perhaps thinking of Blair's error, or perhaps appeasing factions in his own party. But this is not the same situation and has to be judged on its own merits. As a Canadian, I don't love everything about Mark Carney, but I do rate his higher than Starmer in terms of political nous and pragmatism and insight, and I think his response on this has been more sensible.