[anthonys]

Things might be very different in the US, but interchange is nowhere near 2.5% for a debit card in Australia. Maybe that's what is levied to the merchant (or more) but by the time it gets back to the issuer, after merchant service fees and on-charged scheme fees it's more like 0.5% for a debit card.

I could be mistaken but business models built on interchange (I think) have been the downfall of a number of 'neo-banks' from the last 5-10 years. More recently I've seen people adopting a commercial-classified card (or other) for these types of plays for the sole reason of it attracting a higher rate of interchange vs a typical consumer debit card.