> But the difference is that the parties in the US and the UK aren't very powerful in their own regard. Trump wasn't even a member of the republican party until very recently, and he won the nomination -- and Sanders forced Clinton very far to the left before dropping out.

True in the US, not true in the UK -- May and Corbyn had been MPs and members of their parties for years before becoming leader.

> "party discipline", another throughly undemocratic concept, all but unheard of in UK/US parties

Again, not true in the UK