Yep. Power or internet goes out where I live fairly often and you'd have to drive at least an hour to use anything but cash.

Another commenter already mentioned natural disasters, which happen with surprising frequency (I've been through quite a few myself).

Cash fills in society's all-too-common edge cases.

I kinda thought those environments would be less dependent on emergency cash, because they'll have a week's worth of food, backup energy/power sources (BBQs, propane tanks, jerry cans of gas, woodstoves, etc.).

It's people in the cities that get boned when the grid crashes.

Especially if them city folks put all their livelihood into digital cash.