That's because our marketing department in the UK isn't as awesome as the ones they have in the States... have you not noticed that _everything_ has far more fanfare in the States than anywhere else on earth? Everything is so dramatic... including the "notoriously difficult" calculus. It's just their way of patronizing you with "don't worry if you don't understand, it's notoriously difficult" or put you on a pedestal "wow, you must be a wizard to understand that, it's notoriously difficult."

It's just like everything else in the visible universe: A bunch of simple fundamentals put together to make something complicated, wrapped up in a bunch of jargon making it look scarier than it is, like the monster under your bed that only exists in your head.