You're missing the last bit - shareholder value is return on capital for shareholders

The interests of the shareholders diverge quite strongly from the interests of electrical utility customers. It is generally a parasitic relationship where they consume resources that could have been spent improving utility service for the customers, either directly via dividends or indirectly by avaricious behavior on the part of the company in pursuit of their stock price.

> The interests of the shareholders diverge quite strongly from the interests of electrical utility customers.

Unless the customers are the shareholders, as in a co-op. The article's data seems to show that co-ops provide the cheapest electricity, which makes sense because the owners are the same people as the users, so the incentives are aligned.