It's not clear how much direct democracy is really needed in the 24th century. There are few references to elected officials, many more to those who are more likely appointed. I would not be surprised if GR had a cynical view of federalism and decentralization. Perhaps election would be limited to voting for representation to the Federation Council and Federation President. If that were the case, things like USA and UK might only exist if they are useful for administrative purposes, but might have no political existence. It's even possible that the 24th century economy would make devolved governance inconsequential.