The only way you can vote is on election day, which is probably why.
I think you can vote by mail but you need an excuse to do so. No early voting or anything like that.
(assuming these rules also apply to the upcoming primary)
Maybe this is unethical, but couldn't you just say "I'm gonna be out of the country on election day", vote absentee and then just not be out of the country that day, or whatever?
I think it's dumb if they only allow absentee voting for certain reasons. Some people are in the city for election day, but really cannot go vote due to other commitments.