I'll go out on a limb and say those kids never existed, but were enrolled in school and, probably, the welfare system.
Ghost kids.
Not ghost kids. This is typical in every community that burns. You are going through one of the worst times in your life if not the worst.
The last thing on your mind in the middle of the months long chaos that ensues in your upturned life is to contact the school. School records are where those numbers came from. Many people left, enrolled in other schools, enrolled in schools to where they left to, they are not going to contact the previous school.
These things are quite chaotic. I’ve been to a number of these. The numbers of missing and dead are highly exaggerated, and not through any nefarious actions, it’s simply confusion. They always drop dramatically as things progress, information becomes clearer, and things settle down.
Lahaina had a population of 13,000. The demographic in those communities tends to be older. The entire town did not burn. 1000 missing kids just considering those factors was rather high, but I don’t think it was intentionally deceptive. And who knows what were the actual numbers put forth by agencies and how the press may have exaggerated.