I won't disagree with you there (honestly, the whole genre of "Yes, I know that I don't have an 'expectation of privacy' in public; but that doesn't mean that I have an expectation of a 24/7 facial-recognition-camera-network-panopticon-hell" is unfortunately riddled with poorly phrased statements that invite stupid, mostly off-topic retorts...); but I was largely having a stab at trying to articulate the issue they bring up to my satisfaction.
As best I can tell, it comes down to the fact that most of our 'expectation of privacy/no expectation of privacy' dichotomies were laid down when 'no privacy' meant "If you draw enough attention, or somebody who cares is nearby, it might later be remembered that you were there and did X, Y, and Z; but unless it was really good, most people will probably forget pretty quickly or never consciously register you in the first place." The notion of 'no expectation of privacy' as in "There is a stenographer producing a record of everything happening in this room, presumptively the authoritative one, to be kept on file indefinitely" was pretty much confined to the courtroom, and maybe Super Important Negotiations with minutes being kept.
With technology, there has been a broad attempt to apply the (relatively loose) restrictions of the weak, fallible, human 'no expectation of privacy' to systems that offer scrutiny as precise, as long-term, and often a great deal more searchable, than anything in past systems. This produces no end of dubious outcomes (in the same way that the dodgy idea that, just because you use a webmail provider, and thus your email is technically offsite, it isn't among your 'person, papers, or effects', despite being essentially identical in use-case to 'papers'.)
Just to add to the fun, I suspect that there's a little added tension between the fact that "Cons" are a thing that many in the relevant geek communities view with some possessiveness; but the bigger ones are easily large enough, and influential enough, to attract significant outside money looking to do promotion, market research, etc. That flavor of incursion is always a rather tense affair.