Most of the world doesn't put fluoride in tap water. I appreciate that you've been raised to believe it's a "no-brainer and only idiots would oppose it", but there are actual tangible downsides to doing it and now that fluoride toothpaste is widespread there might not even be any upside to fluoride in water anymore.
You don’t need it in the water when you can get it from many other sources. I find it strange that there would be additives to something basic like water. And as I recall there are studies that show too much can be bad too. It’s hard to know your dosage if random things incorporate it as an additive unexpectedly.