Traveling on state funds you are limited to the per diem rate. Anything beyond that and you will have to pay the difference out of your pocket. In my state the per diem is $6, $8, and $20 for breakfast, lunch, and dinner. There is an allowance for high rate areas like SF, Miami, and NYC, and I imagine Hawaii as well. In that case you get an extra $2 a meal. The per diem is ridiculous since it is next to impossible to find meals that cheap in conference areas. There is also a per diem for hotels which for my state maxes out around $275 a night (including taxes). For a place like NYC or Washington DC, you may find it hard to squeak in under that rate. Find a cheaper place further from the conference center and you will wind up paying more for taxi fare every day. Hard to win. At least rental cars in Hawaii are incredibly cheap. About a third the cost on the mainland.
This is true. One can find "plate lunch" in Hawaii at a "lunch truck", or local fast food restaurant, which is nothing like fast food chains such as McD's, and pay $5.00 for a large meal. But you have to know where to go. Something visitors to the islands are not aware of unless they've spent a lot of time in Hawaii.