The nicest thing about cash is that it has an intuitive interface - as you spend your physical stack of paper gets smaller and you instantly get feedback on your spending. Cards simply don't have that. I thought programs like Google pay had a great opportunity to improve the interface. Some way of showing your daily "stack of cash". I would love a widget on my home page or an icon in my top bar that depletes as I spend. Something that turns the 1's and 0's of digital spending into something more tangible. I doubt this will come from banks or cards because it's not in their interest. I think it could come from third parties like Google or Mint because "getting your spending under control" is a great selling point.
I'm now realizing the value of a household expenditures spreadsheet. It's just the place my wife and I set up nearly 20 years ago to record our credit card receipts. Every week, or two now usually, we record our credit card receipts by category spent (gas, bar/restaurant, home, car, fun,...) and then try to keep within our typical totals. It was a bunch of time to set up and get used too, but man, does it give that same effect of spending cash, just weekly. It can hit harder on those weeks we may have gone nuts spending, but over the years we've become more disciplined and that doesn't really happen, or it happens for a "good" reason. Like when we spent thousands in a day to repair our home sewer last spring.