Public Utilities are also run by commercial companies in most of the United States. Verizon, AT&T and Comcast are good examples of that. Most of these American companies must also apply to a governmental board for rate increases. However, these governmental boards usually consist of current, future or ex-employees of said monopoly, who are usually motivated to approve and rate increases.
Also, since they are allowed to make a percentage of their fixed asset investment, they will often inflate those investments as much as possible in order to increase their costs, which increases their profits (as a dollar amount). I once knew someone who worked for the local telephone company who told me that he was instructed to throw or give away all his tools every couple of years because the company would purchase new ones (usually the same tools form the same supplier). This usually happens before a rate increase to help justify the increased cost.