As the coronavirus swept across China in early 2020, several news outlets posted stories about the Chinese government laundering money – not in a traditional sense, but in a literal sense. With so many people touching paper currency, China cleaned and disinfected vast amounts. In other parts of the world, where governments haven’t taken similar measures, many are making a personal choice to avoid paper currency because they’re afraid of contracting the coronavirus. This fear of virus-tainted paper money is only the latest event driving the world toward an all-digital financial system. In late March, as state lockdowns led to...