This is mostly because of that 14-day ticket, for the price of just 7 days. And it includes Memory Maker. I'm not from the UK but I've heard of many UK visitors who go to WDW for the full 14 days. I'm sure Disney is happy to provide them with "free food" if they're willing to pay rack rate for 14 nights
The 25 to 35% is usually only for deluxe resorts right? While that is a lot, you'd still be bleeding money for what Disney charges for those resorts (and no free express pass either!)