> you see the printed receipt through a glass window

I actually believe this is actually the best possible situation.

The voting machine should print a clear, unambiguous, ballot and on-screen tell you to verify it before you officially "cast" your vote. "If the ballot below does not represent your choices, please click <HERE> to request an attendant."

I'm thinking of this more as having printers that print out an unambiguous completed ballot and less as voting machines that "also print out a copy".