"...paying digitally make it harder to keep track of how much youve spent or charged..."
can't agree with that, digital transactions are much easier for bookkeeping
I don't think that's what they mean. When you have a fistful of cash, you feel more attached to it than if it's just a number on a screen. Experiments have shown that people are more likely to take risks/spend money when they don't have a physical representation of that money.