The issue is management of trust. The machine should print out a paper ballot showing your votes in English text. The machine that counts the votes should use OCR to read that text, so that it is using the same text that the voter verifies to count the votes. That means that the ballots can be counted by alternate machines to verify the counting performance. At that point, the trust issue is focused on the counting machine and the custody of the ballots. It is up to the citizens to make sure their county government doesn't mismanage either of those.

Light pens are the correct solution for a voting application - the nature of the hardware prevents misalignment and has no need for calibration. A light pen would also be more intuitive to voters who are not experienced with computer technology. The negative aspects of light pens, such as having the pen dangling around, are not a significant problem in a voting application.