Isn’t the easy reply here that there is no expectation of privacy in public, unlike in one’s home? There are tens, or more likely hundreds of millions of cameras recording outside in the United States.

It's not that simple. If you were in public, going about your business, but someone followed you around perpetually, noting down everything you did, you should feel stalked and harassed. That is exactly what these machines are doing. Being in public means that you're not hiding any one part of your behaviour, but nor are you telling everyone where you've been and where you're going, etc.

it's not about privacy in the moment, courts have already said flock is equivalent to warrantless tracking; it's more about privacy in all time-based aspects of your life: where you go, when you go there and the multitude of second order details you can easily infer from this.