I think the current us-voting thingy is about the former case, to find out if John Doe voted or not. Even that is sensitive info IMHO; as people have the right to vote, they also similarily have the reason to abstain and it is nobody's right to know which was the case.

The current administration's motivation might be to find out what demographic did or did not vote, to strengthen their own base and weaken the opposition come next election.

Also, it is a known-good tactics to go in baby-steps when establishing a dictature, it is a fishing tactique where the opposition is weared out by nipping freedoms out here and there, a little by little...

First get to know who voted and who not, then maybe later find out how they voted and why.