This doesn't make sense for Americans because they use a single currency for everything, but in Europe, there is a benefit to having a revenue stream in a desirable currency which is appreciating relative to the Euro.
To the buyer, the loan looks like 0% because the buyer pays back the loan in Franks or whatever. The bank, meanwhile, gave out a loan of X Euros, and is receiving payments in a currency whose aggregate value is X+Y Euros. Their profit is Y. There's also the opportunity to make even more money selling options backed by these payments.
This is a completely valid means of making money, but it carries substantially higher risk than single currency lending. Which is probably the reason most banks don't want to carry too many of these on their balance sheets.