It's not impossible, and while some forms of secrecy are necessary, I don't think they are "widely considered to be necessary," even if "true democracy" was a well-settled concept that happened to agree with your understanding of it. We just don't see eye to eye on this and likely won't ever.

You're basically not saying anything except, "I disagree."

Voting is the same type of public, political speech that donations are. Indeed, in a world where money is indisputably an overwhelmingly dominant medium through which votes are gained (that is effectively the point of donations), they are practically synonymous.