Many of these graves are very old. Markers would have been wooden crosses or stakes which over time would decay away. Also many of these cemeteries were not maintained so marking locations would have also disappeared over time.
We toured New Jersey a few years back and visited cemeteries where my wife's ancestors lived when they landed in the US in the late 1700's. Many grave stones were not legible and there were spaces in the rows where a person would assume someone was buried but there was no way of knowing who or when as there was no marker. Either the original marker was wood and deteriorated or the site was not marked. Visiting old western graveyards you see much the same.
I am not saying what happened at the schools is right. It is just these sites have been known for some time (as per the truth and reconciliation report) however the foot dragging on production of records and actually undertaking investigative work has now led to a media circus plus a fake leader staging photo ops.
