As you may very well know, we have a lot of "Lunch Wagons" in Hawaii. Even before them, there used to be what we called, Manapua Man. There were several, old Chinese men, walking the neighborhoods with a broomstick-like bar across their shoulders, and on each end of the "broomstick" were five gallon tin cans. One can had manapuas (char siu bao) and the other, rice cakes. They would go around crying, Maaaa-naaaa-pua!
i guess you could say they were out done by progress, hence the lunch wagons. We've got them selling, every type of food. Korean, Japanese, Greek, Hawaiian, italian, American, Filipino...whatever!
However, nowadays, i stay clear of them. Too many calories for me and my age! 
Aloha,
Bob