That’s a good point. Seems like that could be a problem for current ballots too - add a second checkmark to invalidate ballots voting for the “other” guy. Doesn’t seem to be a widespread issue, but detecting it for current ballots would be more obvious.
Maybe that breaks this idea. Maybe ideally you’d maybe want a touchscreen+printer to fill in the bubbles with printer ink and show it to the voter for them to double-check before putting in the stack (or, if wrong bubble filled, put it in rejected stack).
Would love more feedback from people to get a better sense of all pros and cons.
no it's not a good point, it's the complete opposite of reality.
The exact mechanism won’t be standardized, some places fill in ballots with pen today, let the voter feed it into the machine and optically scans to tabulate, and others use a computer that tabulates and (usually?) spools a paper record that’s behind a window so the voter can see that the paper record is accurate. The important part is the actual methodology itself.