Where do you think a rinky-dink municipality gets the money to pay for infrastructure? They turn to capital markets, who will make a profit on the bonds or whatever.
They also don't build transformers in-house; they pay vendors for providing goods and services. Why do you think capital is any different from other services? If a private utility issues a bond, investors in the bond will also make a profit on the bond in addition to investors in the private utility making a profit on the utility.
Where does an investor owned utility get the money to pay for infrastructure? Because they're generally not cutting into profits to fund infrastructure improvements.
PG&E is paying 2.4 billion dollars a year in interest expense (at least in 2023), so it's fair to wonder if that's really any better.