Itâ(TM)s the users that are different.
Apollo software was written for some of the most highly trained humans that have ever existed, who spent yearsâ"in partâ"learning how to operate the Apollo computers.
Meanwhile, voting machine software is for literally every adult in the US with intentionally zero training.  Specifically, the most common user being old, less tech savvy voters.
Put it another way: unless your grandpa happens to be Buzz Aldrin, I doubt he could operate the Apollo computer better than a voting machine/app.  And Buzz Aldrin probably can still operate the Apollo better than a voting machine/app.
Sure, the Apollo stuff was a million times better engineered than todayâ(TM)s junk, but thatâ(TM)s not the difference.  Todayâ(TM)s junk is still a million times easier to use.  And yet, itâ(TM)s not easy enough to keep a bunch of untrained users from making mistakes unanticipated by the developers.  Funny that.
Also, arguing that the lower sophistication of Apollo makes it better ignores the obscene cost of developing that way.  That 1+ MB go app isnâ(TM)t bad because itâ(TM)s big.  Itâ(TM)s big because it does more than Apollo... specifically, it can support higher level logic (you know âoemultiple operations on one lineâ) so one person can write the equivalent of 30 man-years of Apollo code in a day.