Well, that's because he's not on your news or TV.

The reverse situation is not true. You could take any reasonably-aware Brit and the odds are good that they can correctly identify (by job/role, if not pick out of a photo lineup) Sanders, Warren, Trump, Pence, Clinton, McConnell, Christie, Romney, Santorum, Guliani, Biden, Powell - indeed, any number of prominent US politicians past and present.

Compare and contrast:

https://www.theguardian.com/us-news (OK, it's all Trump all the time right now, but that's to be expected)

http://www.nytimes.com/pages/world/europe/index.html

Seriously, no-one gives a crap about the Isle of Man. And that includes the people who live on the Isle of Man.