the bolding is mine, this talkin why a mirialan architect called Teela Kaarz got herself convicted to Despayre (a planet that's essentially a gulag/consentration camp).'Death Star' on page 17-18 (hardcover) wrote:Her "crime" had been simply to back the wrong political candidate in a planetwide election on her world. The Emperor had decided that the man running for office was a traitor, as were his most influential supporters
So while the mechanisms might have been officially free, in truth backing the wrong candidate could cause you to end up into a prison planet where basically no one would go out of their free will.
So while the empire might have not changed the mechanisms of the elections or the structure of the goverment, but it's highly likely that the allowed candidates were mostly "yes-men" who would do what ever Palpatine told them.