> Is it really fair to calculate an annual interest rate when the loan term in question 14 days (literally one payday)?
Yes. Because annual interest rates are the standard of this country. That means you compare the interest rates apples-to-apples.
My credit card is 13% annual rate, even if I only ever borrow money for 30-days at the max. Comparing this platform vs my credit card on an apples-to-apples basis (APY) is just fair.