but every distro I’ve tried has a strong sense that if you’re using the GUI you don’t need or deserve admin controls
It’s not that you don’t need or deserve it. The thing is terminal tools are already available. To get the same stuff with GUI someone is going to have to make that stuff. Most people with the skill to make things like that probably don’t care enough about GUI to be inspired to make such tools. Since using the terminal is easy and natural to them. When it comes to FOSS, since people work on it in their free time with no payment, they are likely to only put significant effort in things that they would use themselves.