I used to do a billing system that processed about $15 million a year. To my horror, I realized when I joined that all chargeback processing involved someone in accounting going through the huge envelopes of chargeback claims + photocopied statements that they received in order to determine what to challenge. The online payment processor they used at the time didn't have any option for presenting the documentation online....

I work at one. I know, sadly.

I think thought that it's a failure of technologists to properly address the challenges of billing.