Earlier quoted context omitted.
In the merchant processing industry, there are frontends (where your transaction initially is routed for approval by Visa/MasterCard/American Express/Discover or by one of the Debit Networks) and backends (where the amounts of these transactions are debited between banks). Square and Stripe are both Independent Sales Organizations riding atop Chase Paymentech and First Data respectively: https://www.quora.com/What-pa…
Don't you need to be a bank to settle funds from issuing banks? That's not what I interpreted you meaning when you said "platform reseller" for processing. I believe Square is a bank now, so maybe they'll stop using Chase.
This platform can get wrapped with many different payment terminals (Verifone, Pax, Dejavoo, Ingenico, etc) or processing interfaces (Authorize.net, PayPal, Stripe, Square, et all).
Square does look to be a bank now, but it appears the only products they are underwriting risk on are loans to businesses, which they immediately try to sell off to third party investors: https://www.cnn.com/2021/03/02/tech/square-bank-business-len...
Kinda surprising, I would expect them to have underwritten their own payment processing, but it might be the case that they don't want to have the outsized liability of chargebacks on their books if a client business goes bankrupt, all to save 2 cents on a $100 transaction.
Perhaps once the US economy slows its rapid economic shift they will consider handling their own underwriting and batch settlement.