ISPs mostly aren’t public utilities, so none of that applies to them. Taxes generally don’t go to them. They’re no more public utilities or tax funded than a company that would come to your house and cut your grass.
It is true that several times in the last few decades the government has handed ISPs some cash in exchange for doing specific things like expanding service to certain areas. It’s more than justified to be mad at them for not holding up their end. That doesn’t make them public utilities, though. The government deserves a bunch of blame for that, too, because it’s stupid and handed a bunch of private companies a bunch of money with no accountability mechanism. Of course they’re gonna take the money and run.
That’s why I’m saying stop trusting the government to fix things like this.