I’m guessing these people are on what PG&E calls a “Balanced Payment Plan.” We pay the same amount monthly, regardless of actual usage. Every three months, PG&E does a true-up and we pay the overage or get a credit for the underage.
I’ve worked on utility billing systems. They are staggeringly complex and not easy to change. These companies aren’t exactly like Amazon when it comes to billing prowess and flexibility.
If they are on the budget plan, it makes sense then. You are paying the same amount every month, regardless. With a credit, or bill at the end of the year. This works in your favor for high cost months, but also can bite you in case of a mega-frankenstorm.