[dboreham]

There have been various cryptocurrency-based efforts (including some of my own) in this space so we must presume that their lack of adoption is the issue rather than lack of available technical solutions.

Why the lack of adoption? I'm not sure but some combination of incentives, inertia and regulatory capture seems likely. Consider for example that the payment mechanism most people use (credit cards) took decades to become ubiquitous and is itself based on an older system (cheques and banks) that is much older. It's still not possible to freely and cheaply send money digitally in the US, but it is in the UK but only because the government made it a rule that banks had to provide such a service.

[jchw]

If there really are attempts at standards that sound like roughly what I am describing, I am definitely interested in hearing about them, FWIW. All I am aware of is the W3C Payment Request API, which is definitely very interesting and in a similar vein, but I really want something that works between parties on the web rather than between web entities and platforms/browsers...