While cash is not an unimportant part of life in developed countries, it certainly isn’t central. The vast majority of Americans, 80 percent, carry less than $50 on them at a time on average and about half carry less than $20. Cash is still king in the developed world when it comes to small dollar purchases- 89 percent of buys under $5 dollars are don in cash, and 58 percent of purchases under $20 involved greenbacks – but paying with plastic pretty rapidly edges cash out from there on up.