Despite the Chancellor's argument, it still doesn't change the fact that they automatically look down on non magic users as lower class, label negative stereotypes on them, kill entire groups of them for the actions of one, and simply shrug their shoulders, or delight in the death of children. There is no reason for them drain so much magoi from children that they die. If these mages are supposed to be so smart, they could simple cut back on some of the magic usage above ground, and set up a rotation system so the Goi aren't constantly getting Magoi drained from them.
If the other magicians were discriminated against in there home countries as well, it makes sense that they would be more likely to buy into it.
From their point of view, the people in the 5th district are living better than the people in the slums, and that's true from what we have seen so far.
But the other magicians didn't see what Aladdin and group saw, they didn't see that mage throw that little girl away like trash. All they saw is a bunch of people in 5th district living it up.