I mean the distinction is pretty obvious. Polygamy overly complicates the structure of marriage benefits, and nobody has the motivation to carve out a legal distinction for them. Though I personally don't care if they do.

Gay spouses were not looking for preferential treatment or special consideration. They were denied the same benefits and advantages a hetero couple is afforded purely because they were seen as gross. It was just a tax on gay people.

> Israel bans both same-sex and interfaith marriage domestically – although it recognises both when performed overseas – if the former is a denial of someone's humanity, is the latter equally so?

Yes? Potentially even more so? I think most people supporting same sex marriage would see a ban on interfaith marriage as abhorrent. That's overly militant religious persecution.