Most US transactions can happen without cash *now*. That has only been the case for the past few years. Do you remember when debit cards were new and hardly any places accepted them? And when credit cards were only used for large purchases? Even when lots of people didn't *have* credit cards at all, and it was not a major inconvenience? The laws about debt and bankruptcy have made it much easier for people to get credit cards when they don't have much money. Alongside of that, there's a lot of encouraging people to use their credit cards frequently. It's only in the last 10-15 years, and foreigners have been complaining about US currency for much longer than that.