Issue is when the government (or hacker, or criminal) decides you don't exist anymore and cancels (or steals) your credits.
The more you are divorced from cash transactions, the less you are aware of the transaction. You pay bills at end of month, and are dependant on your bank or card firm to alert you to irregularities. What happens when they don't alert you?
I avoid an Australian coffee chain in NY because they only accept credit or debit, no cash allowed. I'll buy coffee from a street cart in an instant. The duty of every citizen is to legally avoid taxation, and a cash payment simply makes it less complicated.