I’m on IUP and I realized, they mixed the interest rate in their AppleCare, which you have to buy in order to get IUP, nothing is free in this world, especially not a line of credit. They share the profit from AppleCare with Barclays who underwrites their loans applications.
Oh and I must say, this is my guess, I don’t know how they work internally, just linking dots from the fact that you have to buy AppleCare which is about 150 quid extra. If it’s really interest free, why wouldn’t they just give you the phone alone?