Due to changes in land management from traditional times we have had literal plagues of emu and kangaroos. They are of least concern in terms of population. With all other species in decline these two are really taking over.
We fought a war against them to keep their numbers down (and lost!). https://en.m.wikipedia.org/wiki/Emu_War
If emu meat was going to take off in the USA it would have happened already long ago from imports from Australia. Yet somehow people bought into the idea that emu's are worth a lot of money and you should breed them!?