I think the British and Americans have a lot in common which likely makes us equally susceptible, but perhaps some of the reasons are slightly different. To overly generalise two entire countries:

British: tend to defer to authority, tend to be overly polite.

Americans: tend to question authority, tend to have strong self-belief.

As a theoretical scammer I'd likely be looking at different approaches in the two countries, but with probably the same underlying scam. I imagine this is true for most countries, and I'd be curious to see how much of the approach has to change for different places.

Edit: I should add, I think the American fear of the IRS and the UK fear of HMRC are effectively equal. Everyone's scared of the tax man :D