I always put fragile sticker on double boxed fragile goods. Not had a loss yet.

I don't believe the board furphy that AP staff go to exta effort to mishandle goods.

OP the responsibility is AP's if goods were packaged in accordance with APs advice and the package shows signs of mishandling or other damage caused by AP (water damage for example).

If not APs mishandling, if goods were not packaged appropriately then it usually is the sellers responsibility.