The other day at Dig Inn, a just-opened lunch spot on Broadway and 38th Street in Midtown Manhattan, Shania Bryant committed a consumer faux pas. She placed her order for chicken and brown rice and yams, and when she got to the register, she held out a $50 bill.

“Sorry,” the cashier told her. “We don’t take cash.” Not, “We don’t take $50s.” No cash. Period.

“What?” Ms. Bryant asked.

The cashier patiently explained. Credit and debit cards were fine, as was the easy-to-download Dig Inn phone app. But the almighty dollar was powerless.

“I’ve never experienced that before,” said Ms. Bryant, 20, an assistant to a designer. “I guess we’re in new times.”