I looked to this question about what the blue pill does. Everybody in linked questions says that the blue pill is just a memory eraser and/or a sedative.
The thing is I remember a line in Matrix Revolutions where a "real world" operator scans the Matrix for Neo
Nothing, only blue pills
I saw the movie in French so maybe I misheard the sentence. But if this sentence is true, how do they know people are "blue pills"?
I assume Zion doesn't let anyone exit the Matrix with the war approaching so anybody in the Matrix are considered "blue pilled" or ignorant.
Bonus question : If they are able to determine "blue pills", does locating them have a purpose?