The real reason is people who decide on this are 60+ years old and full of prejudice and fear of new.
They can state the problems of the new but the do not see the problems of the old.
Attack surfaces you say ... manipulating the elections is easy not matter what... comparing manipulation of paper ballots with mouse clicks is false dilemma.
We have no big problems using electronic money.
Q.E.D.
Ok - now do nuclear launch codes.