Say the public grid is notoriously unstable. Electricity is on maybe 50% of the day. (This is in fact true in some countries.) Now the government (who pretty much has sole domain over running utility wires) offers a "deluxe" service, with 100% availability, for the low-low price of a week's worth of food for one day of service.

Congratulations. Now you've stabilized a scenario in which everyone with money and power is sated, and the government has little reason to allocate any resources to improving the service to the remainder of the public.

This is not the same as with roads though, since they are a finite resource (whereas, arguably, electricity can be seen as infinite in this case). You can't ask people to pay for roads which they then can't use because they can't afford the tolls for it. It's already bad enough that so much tax money flows into building roads, which can only be utilized by people wealthy enough to own and maintain a car in the first place. (I'm reading the book "Happy City" at the moment, so this topic struck a chord with me)