OP's argument would be that bathrooms, changing rooms, hotel rooms are examples of places with expectation of privacy.

And if you are walking in the middle of a mall with lots of people around you, that would be an example where there is no expectation of privacy.

-- OP argument put more simply, if you are in a bathroom, everyone expects that that is private. In fact bathrooms have doors and urinals have privacy screens. If you are taking your clothes off, a reasonable person expects to be private

Whereas, in the middle of the mall where there are tons of people, there are surveillance cameras, and other people taking pictures of each other. That would be somewhere with no expectation of privacy