I own property there, I pay property taxes there (at the highest "non-owner-occupied" rate), in my case I'm actively operating a business not (just) a passive investor. Why should I have zero say in how those taxes are spent, or other local governance? I'm not a disinterested bystander.

That’s a fair point, but the ACLU didn’t challenge that aspect of the municipal charter.

Because you have a vested interest in the success of that region by owning land (and a business) at that location. You have skin in the game compared to someone who is just renting and can easily flee to a different city if they vote poorly.