Well, there's already a technical solution for that. You can drop packets which are coming from inside your network but which have ips which don't belong to your ranges. If there was a law that you need to have equipment capable of that and be using it that would be a step in the right direction.
Same for telcos. Make it mandatory and watch them scramble to fix their shitty infrastructure.
Instead of fining them money when they fail to implement the law's requirements make them have to cut everyone's subscription charges in half until they do follow the law to the letter or face the SWAT teams.
