You don't even need a co-op for this. Local, municipal, non-profit power companies are like this too. The city of Santa Clara, in the heart of Silicon Valley, has its own power company. Their rates are less than 1/2 of PG&E (which they are surrounded by) and they were for example offering green energy back in 2005. And as you point out, were much better about maintenance.
Munis will almost always beat any other electric provider including rural coops because their customer per mile is a multiple of a rural operator. It ends up making the coops look terrible because we have to cut an order of magnitude more vegetation for the same amount of customers.
Add corruption to that. PG&E was insolvent (liabilities >> assets) and required a bailout from the state (because nobody would pay more than zero dollars for the company).
That the state didn't simply take the assets and indemnify the previous owners for the liabilities (thus turning it into a giant "municipal" power company) speaks to corruption in CPUC and the state in general.
We may pay more than urban areas around us, I'm really not sure, but not all rural areas around us are serviced by the co-op and they do pay quite a bit more.
We have 3 damns generating power very close by us, two that are pretty big, but I doubt that has much to do with our rates. If anything it's slowed the need for a natural gas or coal fired power power plant nearby, but there are those within 50 miles near the bigger metro areas around us. No nukes close by though.
I really miss being served by SVP.