Cash helps me budget. It's all to easy to be tempted with an unessasary or impulsive purchase with a card.
I carry cash, and pay cash. If they don't want my cash, they don't want my custom. Simples.
I always have a water bottle on me, and some snacks, as being gluten free, it's impossible to just grab a sandwich or pasty if I get peckish, so I don't need to bother about paying for that sort of thing....plus it's cheaper!
I always wonder how people will cope if the machines go down.
No cash, =no petrol, or anything else, whereas if you have cash on you the world keeps turning regardless.