: Why is that not a filter option?
: "Luminary, display all data."
: "Luminary, filter out all Human symbols."
: "Luminary, filter out all geological curiosities."
: "Luminary, filter out all traces of Human ancilla."
: "Luminary, save the report and transmit a copy to High Charity."

: Why wouldn't they?

: This is supposed to be a war of extermination. The Covenant are supposed to
: be a force that can't be fought, only delayed. Having Human survivors crop
: up in every arcology and glassed colony rather undermines that point.

: If I had to reconcile the survivors seen in The Cole Protocol, Glasslands,
: and Escalation with the ubiquity of the Covenant Luminaries, I'd go with a
: combination of factors: -Luminaries are as expensive for the Covenant to
: manufacture as MJOLNIR is for the UNSC to manufacture. Therefore, during
: the war, they were typically installed on flagships or handed out one per
: flotilla. If the ship that carries a Luminary is destroyed, the Covenant
: cannot spot well-hidden bunkers and stealthed habitats. The system is then
: scheduled for a later sweep, which was not always carried out.
: -Manufacturing defects in the Luminaries allow small groups to go undetected
: in certain circumstances. The circumstances change from Luminary to
: Luminary, which is why the Covenant usually assign at least two per fleet.
: -Luminaries have a short operational life, measured in tens of hours of
: operational life before the sensors burn out. To extend this life, savvy
: users operate them on an extended duty cycle, with only a few minutes of
: active scanning every hour. This is how Prowlers usually get the jump on
: Covenant warships.
: -Humans who are near death or in a medically induced coma are registered as
: "dead" by Luminaries, which is why Mike Baird wasn't killed in
: his sleep in Midnight in the Heart of the Midlothian . There are plenty
: of stories about people who recovered from death's doorstep after a
: glassing, only to die slowly and painfully months later as their survival
: equipment wore out and what little food they could scrounge was consumed.
: -After the early stages of the war, bands of refugees journeyed through the
: front lines and set up hidden colonies in exterminated systems. These
: refugees were hostile to or persecuted by the UNSC, and were willing to
: gamble that the Covenant wouldn't sweep through a given system a second
: time through.

Covenant might treat glassing like antibacterial soap and not care if there are still a few blips out there as long as they killed 99.9% of the "germs".