Nobody does have an expectation of basic privacy on the sidewalk and they never have, from mutually disconnected agents like watching neighbors, random photographers, the occasional store camera etc.... The argument isn't even about these things. It's being watched by a vast interconnected network of AI-monitored facial recognition cameras that all feed into a centrally readable series of government databases which are cross referenced with other personal records of people (that can also, by the way, be hacked) and is also sold to bigcorps for intrusive, constant monetization that is a whole different order of privacy violation in any public space. This is what saying you have no expectation of privacy in public completely misses the larger point about... The latter is a much more terrifying prospect and it's well on its way.
Exactly, with the progress of technology we need to codify more nuanced concepts of degrees of privacy to protect the individual from powerful institutions. The standard of "no expectation of privacy in public" was developed at a time when universal surveillance was unthinkable, there is no reason that it should permanently remain the limit for putting constraints on surveillance.