In what fashion has the USG been tracking us?
Not too long ago I traveled through Europe, and came back to the USA with not a single visa stamp in my passport. And no one asked me where I had been.(Granted that my flight to and from Paris was part of the USG manifest).
I've also traveled through many countries in SE Asia, and the most I was ever asked on my return to the US was which country I had just come from.
Unless you're positing that foreign country passenger manifests for boat, train, bus, and air - in addition to foreign visas - have secretly been transmitted to the USG "for some time now", then you are wrong.
I find this new requirement to be an absolute and dangerous intrusion on privacy, and a violation of the 4th and 5th Amendments.
I'm not a lawyer, but it seems to me there is no fundamental difference between one's travels overseas and one's travels within the USA.
Pretty soon we'll be getting exit visa (a feature of countries such as Vietnam, Indonesia, and Saudi) and carrying national IDs for travel between American states.