I refuse to carry cash for many reasons. As I remember, businesses were encouraging people to use credit cards for purchases because they found people spent more money and they reduced their risk of theft. It is a win win for them. If they charge me a fee, I will assume that they are making a business decision to absorb the responsibility of paying their help more so I will feel free to reduce my tip accordingly. That is my rationale, and I am comfortable with that. Businesses should be careful.