I think it is hard to ensure simultaneously the integrity/consistency and confidentiality of the electronic vote. "low-tech" paper ballots are easy to understand (including for elder/non-tech people), and make it more difficult to implement a massive fraud at scale. (Yet on the other hand, I admit that electronic vote makes it easier to implement more sophisticated voting systems, such as Condorcet (https://en.wikipedia.org/wiki/Condorcet_method) or Cardinal voting (https://en.wikipedia.org/wiki/Cardinal_voting)).

Notice that on the other hand it would be comparatively easier to make an electronic registration system ("X has voted", which does not require the same confidentiality), which then could enable people to vote from any voting office within their country rather than having to go to the specific voting office they are registered to.