system
Given the following post, respond as if you're commenting on Reddit:
human
[Halo] Why can't Jackals pilot ghosts?

So, uh... Yeah, I'll admit it. I'm kind of a rookie. Joined up with the UNSC a couple years ago, but never really saw much action. I've seen the vids, though. Helmet cams, satellite imagery, reconstructed battlefield displays, etc. ONI's declassified Spartan POV footage? That's some crazy shit, man. Glad they're on our side, eh? Heh heh...yeah.

Anyway, one thing I noticed was that those purple, t-shaped things...ghosts? That zip around all over the place? They're mostly piloted by grunts, those little monkey guys with the freaky faces. Now, I may or may not have taken a snooze during the basic introduction course, but I remember something about a caste system, right? Like, the elites are at the top, jackals in the middle, an' grunts on the bottom. I think that's the gist of it.

So, my question is, if those grunt thingies are below jackals in the Covenant, how come they get to ride ghosts, and all the jackals get are those wimpy little shields?
gpt
Your understanding of the caste system is flawed. The Jackals aren't so much on the middle but rather mercenaries/privateers. The Elites and Prophets don't trust the majority of the Jackals (they are of the belief that, given the opportunity, a Jackal would sooner "lose" heavy equipment such as Ghosts in battle and somehow bring the "lost" equipment to the black market) and so will not give them heavy weapons or vehicles. 

While the competence of Grunts leaves much to be desired, they are at least trusted by the upper classes of the Covenant.