For a serious reply, I rarely carry cash, for the simple reason is I most of the times, I wont need it
I carry very little cash. Why? Because when you put cash in your pocket you suddenly notice you don't have any and no clue where it went! So I use my debit card for nearly everything. That way I have a record of my transactions. Since I am consulting and have a home office, I can write off a lot of stuff for home and car expenses too. So I need records.
As far as places that don't take cards in the 21st century... I go there exactly once. And when I find out they don't take cards I give them an earfull and let them know I'll never be back. I can't imagine being so business stupid. Idiots don't understand how much business they have lost over that 3% fee. They've lost much more!
And I think some of the cash vs debit/credit is old school. And some of the folks that squawk the loudest that they'd never own a credit card... well, they aren't credit worthy. Recently the young guy at work, in his 30s asked me why George and I would spend cash in the cafeteria. It was beyond his understanding. Me? I was just spending off some cash I had left over from going to a model show!