FedNow doesn't allow any more or less tracking than what's already possible through the Fed's visibility into ACH. So for the purposes of FedNow the entire conversation is off-topic.
Anyways, you missed the point.
The anti-new-technology and anti-gov-technology response to privacy and control is misguided. Corporations will fuck you, left unchecked, and governments will fuck you through corporations. There is no technical solution to political problems, and physical cash vs FedNow vs digital currency is a suite of technical solutions.
Trying to solve a political problem by eliminating technology is literally the same thing as trying to solve political problems with technology. The fallacy is in focusing on technology where the actual problem is political.
The problem is political and needs to be treated as such. The solution is building and maintaining political consensus in favor of strong privacy and personal property rights, not carrying around a billfold full of physical cash.
Anyways, it's not (fully) about information sharing. It's about control. It's the difference between read access and read/write access.