> Online voting seems like such a simpler approach.

It isn't. Bruce Schneier has written about how online voting is a terrible idea in general [0], and how real-world attempts at it are often woefully incompetent. [1][2] Voting should remain paper-based.

[0] https://www.schneier.com/blog/archives/2018/04/securing_elec...

[1] https://www.schneier.com/blog/archives/2019/12/election_mach...

[2] https://www.schneier.com/blog/archives/2020/02/voatz_interne...