Same as property taxes. Sure, the tax on a parcel of land is typically public information, but I would consider it very rude to ask a friend how much they pay (in most situations). But all I have to do now is type their address into zillow, instead of having to request that information from the county treasurer's office.
That information was never truly private, but it was private enough that most people would consider it to be so.
It was indeed very rude to ask a friend that, and I still consider it very rude today to do that.
And this is a problem. It is a bad thing, not a good thing.
So my point still stands. Both voting information and property taxes used to be things that were defacto private, and I hope that they continue to be defacto private in the future.
That information was never truly private, but it was private enough that most people would consider it to be so.