I was surprised to find out that placing cash or check in a card presented AT a funeral OR a check in a sympathy card MAILED TO the bereaved IS A QUITE COMMON CUSTOM in the Islands - and here is why:
Most funerals in Hawaii involve a catered meal AFTER the service. These affairs typically involve many different ethnic foods as Hawaiians are quite mixed in their backgrounds. Not only that, but we are not speaking of "tea and crumpets or a turkey sandwich-let. We are talking a full catered meal, with sit down service, soft drinks of several varieties, MASSIVE amounts as some of us (Hawaiians) can pack away the food at a dinner. I've heard that such a meal can cost the "family" $25 to $45 per head!
One of our closest friends passed quite young (only late 60s). He was a clergyman and was known not only by his large congregation but by business leaders, politicians, other area church leaders, etc. It was estimated that over 1000 people attended his memorial service and I would guess most of them attended the meal afterwords. Multiply 1000 folks by even $25 and you begin to see why most folks slip $20, $30, even $100 in their sympathy card. The widow would have been expected to cover the cost of the meal.
That's WAY more than most folks pay these days pay for an "average" mainland funeral (I have heard $8K to $10K for a "traditional" viewing, embalming, caskette, burial service, funeral cars - a two day affair in many cases.)
It's true that cremation is quite common in the Islands, saving much of the traditional costs BUT there are exceptions. Our best friend in the Island buried both her parents within 2 years. Costs were at least as high as on the mainland PLUS the meal. You can be assured DW and I enclosed $100 cash in our sympathy cards AND we helped by arranging flowers and decorations at the funeral chapel and also helped serve the meals.
It's simply a cultural difference that many malihini are unaware of. You would never see a solicitation for gifts, but it's understood by kama'aina that it is customary. YMMV