First off, everyone has something to hide. Otherwise people would be fine with allowing the police to randomly search their houses. See: Three Felonies a Day [0]

A few years ago I went back to carrying more cash. I had realized that debt cards don't provide enough protection against the card info from being stolen (it could take a week to get your funds back). Credit cards have more protection, but after having to replace my cards multiple times, it was just easier to pay for my lunch and gas using cash and not have the hassle of contacting all my recurring payment businesses repeatedly.

[0] https://www.wsj.com/articles/SB10001424052748704471504574438...

Lots of people use cash because it's better for the businesses that receive it to not have to pay a significant processing fee of 2%+. When a restaurant might only run on 5% margins, 2% off the top is 40% of their profits.