The OP's '[2] Inaccurate Generalization' rider definitely needed to be there ;-) UK universities grade in many different ways, often based on course and project work. I'd say that the LSE's exam-only option is in the minority. For example my degree came out of a combination of closed book exams, individual & group projects, and open book essays. However it is rare for there to be continual assessment of coursework throughout the whole degree. It's generally based on a set set of special case bits of work near the end of a term/year.
That said — in my experience — the course work that UK universities that's much less susceptible to cheating in general than some stuff I've seen from US universities. Work varies more year-on-year, and the kind of work involved are things like essays, projects, etc that are harder to copy in a sensible way. I don't think I did a single multiple choice test in my whole degree.
He's spot on about the difference in expectation on top grades though. I've had some… interesting… chats with US students in the past when they went from all "A"s at their US institution to 70-80% at UK ones. Not so much because their answers were wrong — but because they're answers weren't 'excellent'. It seemed to cause an enormous amount of stress for them!