Having a merkle tree and voting from your device instead of a polling station is not just more convenient - it's more secure too. Everyone can verify their vote was counted!!
And right now? Right now we have a government database of who voted for what. That's crazy.
With electronic voting, I can't be sure my vote got counted, and even less sure others weren't tampered with.
And now do both things _publicly_! For money (or others things you own) you will need a Torrens-like title system with a replicated database among your fellow-citizens. For voting - it will be a database replicated on DVDs (or something that can be read, say, by a microscope:)
You may be astonished how secure that will be.
Have they told you about it?
I'm not sure what the choice of media has to do with anything.
Who has told me what about what now?
Biometrics, seriously?
Biometrics are only a one-time proof when eg you are issued a token. They can be replayed later and can't be used anywhere except where there's a physical security guard preventing tampering. And even then you trust the security guard.
Obviously you use your device, and you can lock it with a password. You can use two factor authentication.
It's straightforward, really. You sound like identity has never been solved electronically.
If anything, holding a physical paper id document is far less secure than a personal device with your private keys in the Secure Enclave.
Imagine bitcoin but with votes instead of transactions. Boom.
The bad part about that is that if I can validate my vote after the fact, someone else can also demand to see what I voted for, and that opens the door for vote buying, intimidation etc.
As for rubber hose crypanalysis, that is possible now.
Buying votes is already done.