[pandaman]

It's pretty simple really. Consider two scenarios of buying a $100 item:

a) pay with a 2% reward credit card

b) pay with BNPL scheme with a 3 month term.

In the scenario a) you effectively paid $98 right away and in the scenario b) you pay $100 but after 90 days (let's say you don't have monthly payments for simplicity). For b) to be no more expensive than a) you need a way to make at least $2 from a $100 investment in 90 days. This means that whatever investment you make with the $100 has to yield 8% annually. Even though you withdraw money after 90 days.

If you have monthly payments you need even higher yield to compete with the 2% reward. E.g. if you pay $33.33 every month then you need to make 1% yield per month to collect $2 off your initial $100 in 3 months: you get 3 months of yield from the final $33.33 payment, 2 months of the previous payment and 1 month of the first payment for total 6 months yield from $33.33. That's 12% annualized yield.

[RC_ITR]

You’re not answering my question about cash.

[pandaman]

What is your question about cash? There is no APR on credit card purchase in this scenario. There is also no APR on cash purchases. If you pay cash you pay $100 and without delay so you just lose 2% discount from the credit card or any chance to make any interest from your money on BNPL.