Why can't I use screentime or some other controls to fully disable hotspot on the iPhone?

It makes no sense to spend time setting up a lot of restrictions under Screen Time if your kid can enable the hotspot and do whatever they want on a different device. I've seen a number of posts over the years and Apple and various helpers always say something about asking your carrier to do it...but that's not actually an option for, as far as I can tell from looking online, any of the major carriers, at least in the USA. It's really not a big ask: when my child is at home, I have restrictions on the wifi. I have restrictions on their phone under Screen Time. I would like them to have the phone available; and I would like the phone to not allow them to bypass the rest of my restrictions by simply turning on their mobile hotspot. I'm not asking for any low-level change, just the ability to lock a setting in the "off" position. It can't *possibly* be that difficult.

Failing that, if Apple believes that it knows better about having personal hotspot always available to be enabled, it should run everything through the restrictions I have put in place, not allow the connecting device to connect to anything the phone itself wouldn't be able to use. I believe that would be *much* more difficult to implement, but, it would also solve the problem. ... I'd prefer the easier to implement solution, though....