It isn’t literally slavery
How would you define slavery? Do you see it as only applicable in the context of commodity production?
Candidates that are selected run unopposed, on a “yes/no” basis
I may look more into the book. Curious if you know of any data on how common it is for candidates to lose an election once nominated? I have to say, even the Yes/No voting is done properly, the lack of an open primary or similar seems to preclude the idea of "direct elections".