Since the US is (nominally) a democracy, many people not that into civics often think that voting is one kind of thing in the US whereas it's actually fifty weird fiefdoms of rules and regs.
In Vermont it's actually HARD to get off the voting rolls, even if you want to. We don't require ID, we don't make you vote all the items on the ballot, we mail you a ballot for the general, we don't make you declare a party, we have tabulators. not touchscreen machines. It's no wonder it's confusing.