Right. Infeasible in the sense that both parties have to understand and agree to the terms. A paper check is an immediate and clear documentation of the transaction.

I guess one other option Simple and other banks offer is to mail a physical paper check to a person or business. Again, it is unlikely this would be acceptable when the terms are "due upon receipt" and credit/debit is not an option. I think we are moving away from these scenarios, but we still live in a world where paper checks may be a necessity in some situations and certainly very convenient.