I am in no way condoning fraud, and of course any people claiming fraudulent GST refunds should be penalised (and if possible more severe punishments for the scheme's promoters)
But, on my reading of articles about this, it appears that many of the people claiming the refunds may have been people doing it tough during the pandemic (and possibly not having good financial advice/knowledge). Of course, their behaviour was clearly illegal, and therefore much easier for the ATO to penalise, rather than going after those who can afford smart accountants/lawyers to help them operate the grey area between avoidance and evasion.