This is still very much an open problem. Paypal, Square, Venmo, Google Wallet, PopMoney all possess idiosyncrasies. As well as friction arising in enrolling both parties and setting up bank account info. I prefer using Zelle as it's fast but there is a limit of $2500 per transaction.<p>Ideally you need a smart contract that creates a pool of funds that can be drawn upon via some secure identity mechanism. Instead of pushing the money out, participants can pull their allotments at their convenience. Implications for UBI are also extant. Using something like Paxos Stablecoin it may be possible to realize global, instant, feeless digital payments. But again every participant needs to be on the same standard.