The practice of making public whether someone has voted dates back a very long time. There were practical reasons for it when it originated, and many of those remain valid today.

Originally, everyone in town knew most everyone else and could see them physically walking into the polling place. So long before electronic records were kept, the question of who voted was public information.

Even today, I run my local polling station and I know and recognize a significant portion of the voters in my precinct.

The fact that the list of who votes is made public protects against several kinds of abuses. It goes a long way to protect against "dead people voting" and other kinds of ballot box stuffing if the list of voters is public so anyone can review it and potentially catch such abuses.

I suspect the missing angle is that people are more likely to trust claims made to the public if, in principle, those claims could be verified by the public.

Of course it's pretty impractical that a bunch of concerned citizens might gather together and check the published data against how they each remember voting. But preserving the possibility in principle makes it easier to trust the published results. It gives a would-be deceiver yet another thing to worry about.

Its a trade-off I'd have opted into had I been asked. Though I'd feel a lot better about it if I had been asked.

I was thinking the same. It's not as if visibility into whether someone voted or not has driven voter turnout significantly. Hell, I'd assumed this was private until I learned otherwise recently.

But it's such a specific structure, clearly there was an objective in mind when it was imlpemented.