[BonzoHansen]

Matters not, now we are in red herring territory. We have moved to semantics and irrelevant information. From your example, we could also add charge back costs into your cost calculations. Charge backs are the #2 reason some places don't take amex (following transaction costs). Amex will side with a card holder in a dispute regardless of how much proof a vendor has. I've seen it first hand many times. There will be a certain about of charge back, even if you run a perfect business - people bitch, CC bow to their card holders.

I'm not sure how you save 20% using a credit card in normal everyday situations - let's not talk about short term special offers and all that. I can clip coupons too, but now we are way off the mark. You can't use situational anecdotes don't support general theories. You are not getting 20% cash back from your cc on every purchase are you? What one?

Bringing it back more in line with the OP questions, the point is there are valid reasons to need access to cash. Is cash needed less these days? Sure. But there is still unequivocally a need for cash access, highlighted in previous posts.
*cash businesses/business does not accept plastic
*personal preference, spending control
*tipping/service payment
*convenience