At 55 years old, I am certainly not a yuppie, and I rarely carry cash. I use my debit card for pretty much everything. It is quick, easy, and I have a record of every penny I spend, and where I spent it. My bank accounts are linked to Quicken on my computer, so at any time, on any day, I can look at my spending habits, which helps me change spending habits, if needed.
Plus, if my wallet is lost or stolen, I can call my bank, and immediately, my debit card becomes useless to anyone who has it.
BTW, a couple of months ago, I found someone's debit card on the ground. I called the issuing bank, and told them I found it, and they canceled it. If I had found a 100-dollar bill on the ground, what could I do for the person who lost it? Nothing. That money would almost certainly be lost to them forever.
I think cash is slowly going the way of the horse and buggy. It is like land-line phones -- some people won't give them up, but I ditched mine at least ten years ago. My iPhone is all I need.
CD