You might be surprised how helpful it would be to know the most recent area a person stayed, to remind them before their visa expires what their options are, and to know within a month that a person that should have checked out of the country did not do so.
You are correct - I would be surprised. The most recent area is pointless in a country where you can catch a bus or train from one side to another in a few days. Reminding them their visa is about to expire can be done using the email address/contact details that all US visitors have to provide when they get their ESTA or visa in order to be allowed entry to the country. Knowing to the day that a person that should have checked out of the country and did not do so is already recorded trivially at passport control. None of these tasks require the multimillion dollar cost of setting up and manning checkpoint offices across the country.
Your assumption about ankle bracelets is quite ridiculous. If you want to get modded informative, don't make shit up that isn't reasonable. I understand you don't like Christie, I'm not a big fan but at least I don't have to resort to hyperbole to justify my opinions.
On the contrary, my opinion is that ankle bracelets are pretty much the only reasonable way to make a scheme like this work. The self-driven check-in option you've proposed is just a huge waste of money with no useful outcomes (as I said before - probably just a boondoggle to enrich Christie's campaign donors). I don't follow US politics closely enough to like or dislike Christie or even know who he is, as my country has enough political problems to fill my news feed. I'm just pointing this particular idea out for the BS that it is.