And explicity notes that it's the relative scarcity of them that matters.

> Decades later, in United States v. Jones, 565 U.S. 400 (2012), location-tracking technology crossed the line from merely augmenting to impermissibly enhancing. There, police used a GPS-tracking device to remotely monitor and record a vehicle’s movements over 28 days. Id. at 402–04. Although the case was ultimately decided on trespass principles, five Justices agreed that “longer term GPS monitoring . . . impinges on expectations of privacy.” See id. at 430 (Alito, J., concurring); id. at 415 (Sotomayor, J., concurring). Based on “[t]raditional surveillance” capacity “[i]n the precomputer age,” the Justices reasoned that “society’s expectation” was that police would not “secretly monitor and catalogue every single movement of an individual’s car for a very long period.”

> Thus, Carpenter solidified the line between short-term tracking of public movements—akin to what law enforcement could do “[p]rior to the digital age”—and prolonged tracking that can reveal intimate details through habits and patterns.

Put enough of them up, and the software to track between them, and you're in "enables police to deduce from the whole of individuals’ movements" territory.