I'm with you. My wife and I use a credit card for random regular spending. We never go past our weekly budget for it. And I pay it off weekly. In the course of a year we get back about $500 to $600.
Of course, that's not enough of a reward to offset bad spending habits if a credit card increases spending. So it should be a person by person decision.
When using cash they should keep receipts to track spending too.
I hate it when I have , say, $50 in cash on me and in two days I have $15 and scratch my head and wonder where the 35 went. HA
Being disciplined to not use a card but use cash only will force a person to live within their means. To do so will take discipline. Discipline can also allow a person to use a credit card to their advantage.
My wife and I use a credit card to pay for just about everything. It gives us 2% cash back, which is why we put virtually everything on the card. We pay the full amount due on the card every month and as a result never pay interest. We live below our means. The day we can't pay the card's balance in its entirety is the day we'll cut up the card.