Sure you might make a few quick wins from careless users but overall it creates an environment of distrust where users are watching their pennies and lots are even just standing off.
I can accept that with all the different moving parts this may be a trickier problem than a pre paid pump, or even a Telco, and while to a product manager this might look like a lot of work/money for something that “prevents” users overspending.
But we all know that’s shortsighted and stupid and its the kind of thinking that broadly signals more competition is required.