The actual failure reason reads: "Exterior, Structure, A Pillar, Corrosion, Left Front". The inspector said I needed to repair it and only then they'll put a new WOF label on.
Although I am glad they noticed that rust and let me know so that I am repairing it now, I am wondering if that was a valid reason to fail a WOF. Because VTNZ is not a garage that would aim to sell me their repair services I did not expect them to fail a vehicle without a safety-related reason.
According to NZTA, for the purpose of WOF, rust is only a concern when it might affect safety (e.g. rust on load bearing elements, safety belt fittings etc.). So, it that gutter above the left front door related to structure or safety in any way?