sushe -“The only reason you still don’t hear about it too much today is because they don’t want to go to jail from the goyish (or in the case of Israel, the Zionist) authorities. They have no problem religiously having more than one wife.”
This is your mistake. I pretty sure the Gemorah Assurs marrying more than one wife in a place where it is not the Minhag HaMokom. So in the arab countries – the Sefardim can have more than one wife. In countries like England they can’t. The question would be in the US and Israel.
Israel, if you don’t hold of the Medina, so they would have the Din of the arab countries around them. If you hold of the Medina -then you can’t marry two wives because it’s not the Minhag. The US is a fairly new country, but it’s probably Assur here because they might be considered going after England’s Minhag.