I AM a techie and even I would take RH on their word when they say 'instant'. When I send money to India from a US bank account via an intermediary (so that neither the US bank nor the Indian bank are first-party to the transaction) it is removed from my US account (in USD) and reaches my Indian account (in INR) within seconds, and I can see the balance in my Indian account and spend it right away, so I have no reason to believe it can't happen domestically when it doesn't even involve a currency change.

It's like this in most parts of the world. It's only the perversity of the American banking system where money transfers in this day and age routinely take 2-3 days and no one thinks there's anything bizarre about that.