i think people are dismissing how big of an issue it would be if your credit card and ATM card stopped working. Bad things happen and you can't just go home and wait for the bank to handle any issues.

I carry about $100 concealed somewhere in my day pack that I always have with me but don't spend. In addition to that I like to have about $50 on me for little purchases and campsites. I also carry a CC and ATM card in different places.