I guess it depends on what the fine is for not complying. For your above scenario to make sense, the fine itself would have to be more than the cost of installing the line. Otherwise, they would just pay the fine and forget about it. Also, there would need to be timelines for how long they can take to get the service working. If you have to live in the house a year without good internet before they get the service up and running then the law isn't very helpful. Also, what happens if you move in in December and they can't install the lines until March when the ground has thawed? Also, there's no law saying how much they are allowed to charge you, and they often don't charge the same fees for everybody. Once they've installed your lines, you're basically a slave to paying that provider's rates. If they want to jack up the rate 6 months down the road to recoup costs, there isn't much you can do about it, other than try to get some other provider to put in lines as well.
Actually there was only one important caveat: "Pass a law that if a service provider says that they offer service to an address they must do so by law." So the goal is not to get service to every address in the US, the goal is to make paying the fines more painful than generating a correct national broadband map. Correct map in hand, consumers can make a more informed choice and national providers will have a more flimsy straw man from which to argue behind.