A tattoo is probably the most permanent personal statement it is possible to make. Unlike clothing or a hairstyle or a piercing of the lips or nose, a tattoo cannot simply be discarded. Removal is an expensive and painful procedure that is quite likely to leave a stain in any case.
Its permanence makes criticism seem unkind and pointless, which is why people who would never scar their own bodies generally respond politely and even supportively to those who do. But an employer cannot afford to be polite to "body art" that might damage the business.
Air New Zealand has been widely criticised for turning away an aspiring stewardess with a moko in the skin of her forearm. In response the airline says it is reviewing its policy. It will be weighing up whether the woman's complaint has done more harm to its public image than tattooed cabin attendants might do to its business. In other words, it must assess whether the tolerance people profess in public truly represents their feelings.
It is true, as the Prime Minister said, that tourists to New Zealand who meet Maori culture will see lots of tattoos. But Maori culture presents visitors with many gestures and modes of dress they probably would not appreciate on the national airline.