Earlier quoted context omitted.
Your ideal voting system is vulnerable to coercion ("log in and show me who you voted for or else") and phishing. Voting systems should provide confidence to voters that votes are counted correctly, but not permit anyone, including the voters themselves, to learn how they voted after the ballot is cast.
I love voting by mail, but I don't understand how that's legal since you could just coerce someone that way? Force them to vote by mail, watch them fill out the ballot (or fill it out for them), and mail it in.
You basically need to hold someone hostage or under total surveillance from when the ballot is mailed to when the polls are closed to avoid them just sending in their actual ballot afterwards.
With an electronic voting system the window of time you have to hold someone hostage is much shorter - simply force their vote an hour before the polls close and then hold them prisoner for the hour.