Most customers do not fool around with counting money and the nuisance of change
I think you missed the point. The reason military organizations are planning for operations the old fashioned way is because of the potential or likely disruption of cyber networks. (Read: GPS)
If cyber warfare expands to the economic instrument of national power (that is very likely) not only will the cashiers be counting change but the old fashioned cash register will be back in style. Remember writing hand receipts from a pad?
I would not get comfortable using the credit card network. Plan on cash. At least for a while anyway.
I know....I am a doomsday person. Personally, I always plan for the worst and hope for the best.