[probably_wrong]

But how do I know that no one is correlating those GUIDs with my personal information? And more important: how do you convince a common citizen that their votes are not being tracked when there's a unique identifier right there?

The way I see it, it's a system that only works in elections when it's not needed. Otherwise, all you need to suppress people's votes is some thugs saying "we have men on the inside - if you vote for someone else, we'll know". It doesn't need to be true, just plausible enough to make people think twice before voting.