BIK,
Not every tradesperson in Australian aviation belongs to the ALAEA, many structures trades belong to other unions, we are all trained from the day we start as are apprentices cautions when working with aluminum alloys.
This is not the first time this type of defect has occured overseas, Boeing have many reports on record.
Thankfully a trained eye picked this defect up, it my have been a AME, who carried out the inspection and not a LAME, I would choose your words carefully regarding unions and safety.
In any case I will pass your post on to the ALAEA.
VTM