The stress on individual was to denote that you can't, for example, get a warrant to search every American's home. It has to be limited in scope.
The judge was saying that the police needed probable cause and a warrant to search the Flock system because it's dragnet surveillance, similar to needing a warrant to access cell phone location data. [1]
Just because you don't have an expectation of privacy while moving in a public space doesn't mean you don't have an expectation of privacy for all of your movements ever in every public space. That scenario wasn't possible in the 1700s.
For an individual today, it's fine for the government to tail someone without a warrant. [2] It's probably not fine for the government to put a long-term GPS tracker on your car without a warrant (probably because the issue was sidestepped with trespass). [3]
Even Alito notes that in the past it would have required too much labor for the government to surveil every movement of an individual for a long period of time and so society has the expectation that the government is not doing that. [4]
[1] https://en.wikipedia.org/wiki/Chatrie_v._United_States
[2] https://en.wikipedia.org/wiki/United_States_v._Knotts
[3] https://en.wikipedia.org/wiki/United_States_v._Jones_(2012)
[4] https://www.law.cornell.edu/supct/pdf/10-1259.pdf#page=33
The judge was saying that the police needed probable cause and a warrant to search the Flock system because it's dragnet surveillance, similar to needing a warrant to access cell phone location data. [1]
Just because you don't have an expectation of privacy while moving in a public space doesn't mean you don't have an expectation of privacy for all of your movements ever in every public space. That scenario wasn't possible in the 1700s.
For an individual today, it's fine for the government to tail someone without a warrant. [2] It's probably not fine for the government to put a long-term GPS tracker on your car without a warrant (probably because the issue was sidestepped with trespass). [3]
Even Alito notes that in the past it would have required too much labor for the government to surveil every movement of an individual for a long period of time and so society has the expectation that the government is not doing that. [4]
[1] https://en.wikipedia.org/wiki/Chatrie_v._United_States
[2] https://en.wikipedia.org/wiki/United_States_v._Knotts
[3] https://en.wikipedia.org/wiki/United_States_v._Jones_(2012)
[4] https://www.law.cornell.edu/supct/pdf/10-1259.pdf#page=33