Iowa and Georgia are not deregulated so you only have no choice from your utility, unlike Texas, Illinois, Ohio, and most Northeastern states.
There is finally some push to change that in regulated states, though. It's called community choice aggregation, which has been highly successful in California but not in other states, because the other states that allow them are all deregulated. Now, though, AZ, CO, NV, OR, WA, and MI are all considering legislation to allow it.
The way it works is that municipalities or counties can take control over how their energy is procured, so that they can offer lower rates and/or higher levels of renewable energy. Because utility rates are set by the state governments, they can't really respond to this quickly. The utility is still responsible for basically everything else. Customers can still choose to just remain with the utility but generally there's no reason for them to do that. Because these programs work through government entities, customers can be assured that their rates will remain stable whereas in deregulated states, some of the energy suppliers are unfortunately quite shady and unethical by offering low intro rates before they get jacked up.