State statutes lead to some peculiar situations.
Arizona requires photo ID but a passport is no good. AZ also requires that the photo ID must have the voter's address; U. S. passports don't have that.

A bit of humor this morning when the South Carolina governor was turned away for lack of proper identification; he had to make a second trip. Not sure what the requirements are for ID in that state.

Not completely true about voting in all countries being restricted to citizens. When I came to Canada I did not become a naturalized citizen for some time because there was a possibility that I would be transferred out of Canada to another Company affiliate.
Provincial law allowed me and other non-citizens to vote in local city elections if I was a property owner, which I was because I bought my house. When I came, about 12% of the city population held U. S., and an even larger percentage had UK citizenship. We all voted in local elections, and if I remember correctly, British citizens could vote in all elections if they owned property.