But you also generalize a lot. A more appropriate title could have been “ … the Unbanked in the US Are Being Left Behind”.
In other parts of the world, Africa in particular, as long as you have a mobile phone number then you can transact cashless. Because apart from banks, mobile operators also operate mobile money systems. Mobile money wallets.
In fact most cashless transactions in these places, happen without a bank, as you know it, being involved.