The details vary substantially by type of utility and jurisdiction, but generally a public utility is subject to far stricter regulation than internet service providers which are regarded as a competitive industry.
A key example would be requirements for tariff approvals: public utilities are generally not permitted to make their own pricing decisions, instead they need to publish a tariff and they are not permitted to modify the tariff without petitioning the regulator for permission. The regulatory authority generally has broad authority to order utilities to do whatever it believes should be done, and has to approve almost all changes to the service, which the utility must justify as beneficial to customers.
Take a look at your electric bill, for example. Generally there's an interconnection fee and base rate, both of which come directly from the published tariff approved by the regulator. Due to real changes in the energy market there will also be a "fuel cost surcharge," this fee is calculated based on generation costs according to a formula included in the published tariff. If you have any dispute about the pricing or quality of the service you can take that complaint to the regulator, many regulators require that the utilities provide you that phone number as part of your bill.
Then look at your internet bill. The rate on it is whatever the ISP wants, and they have no requirement to explain it to you, except for a few mandated taxes. They can raise and lower it more or less at will, subject to your contractual protections, which are usually minimal. With most incumbent ISPs it is standard for the rate to increase significantly after 12 or 24 months. If you have complaints, there is a small chance you can take them to the FCC under certain regulatory authorities the FCC has exercised, but for the most part your only option is to find another provider.