Hurricanes and other natural disasters remind us that our ambitious human efforts to build financial technologies and new forms of digital money can easily be rendered futile. Paying for Uber rides with a contactless card, trading Bitcoin, and using Venmo and Cash App to make purchases can often be a mechanical, effortless exercise. In a disaster zone, however, all of this is vanity. Surviving natural disasters requires citizens to spend money on food, water, and other basic necessities — and doing that without cash on hand is an unexpected and impossible dilemma. When natural disasters shatte…