mainly because the results would be undeniable
Would they? what if the network is being controlled by the goverenment it self? 51% attack would be an easy way for them to manipulate the results... Unless they use a 3rd party blockchain like ethereum. There is nothing stopping them to manipulate the results.
The network would not be supposed to be controlled by a government or any other institution. One of the purposes of a decentralized ledger, is a consensus of replicated and sync'ed data spread across several participants, as you know.
Regarding a voting system, we could imagine for example citizens being the main participants of the network. After all, they are the most concerned. If citizens don't want to participate in the security of their data and the system then it's another thing. It's like refusing to vote but complaining about the current political system.
In fact, I don't find fair to see something else (entity, institution, govt.) than the citizens used to do it