Giving each tourist a flower wreath (it’s called a lei, by the way) is too expensive, and the rules of conduct at airports have become stricter.
Only some companies can meet passengers with flowers at the ready, and even then, the airport management can forbid them to do so.
If you want to receive a wreath upon arrival, you need to agree on this in advance. They say that this pleasure is not cheap. But in a restaurant, there is a chance to get such a necklace for free: the staff can give it to the birthday boy.
Tourists perceive flowers as an element of the entertainment program, but for Hawaiians, lei is a very important and symbolic thing. Local residents receive a wreath in honor of important events and will never wear it just like that.