I don't hear anyone saying that the government is trying to do away with cash, but the retail arena as a whole is embracing electronic payment, to the end that the normal folks find it more convenient to put the card in the slot and pay once at the end of the month. Add to the mix the incentives like cash back or airline miles that the card companies offer, and the push to abandon cash is very real. Write a check? They run the check through their machine for an electronic transfer and hand it back to you on the spot. It's a debit card without the card.
The point is you say "....if I don't have the cash", but I'd offer that "having the cash" means that you have the funds to buy without credit, but when you pay it will be with your card. I know for me the stack of $20's I carry in my pocket don't get used for month upon month! I'd venture a guess that if you gathered 100 millennials in a room you'd have a hard time coming up with $500 in cash! Uncle Bob's spot on with his analysis, and Seth's comment about Venmo & PayPal reinforces the reality.