It's probably because sugar cane tends to grow in fields. In Hawaii, a field is already pretty much ecologically ruined. On the Big Island, there are fairly lar

It's probably because sugar cane tends to grow in fields. In Hawaii, a field is already pretty much ecologically ruined. On the Big Island, there are fairly large efforts to reforest areas that were previously clear cut to produce fields for cattle and sugar cane farming. Coincidentally, the only place I've ever seen sugar cane spread like a weed is these clear cut areas, it doesn't seem to be able to spread into forests or diverse ecosystems. As such, it makes sense that it wouldn't be seen as being as invasive as something like a christmasberry tree.