You'd also need a business license and probably a food specific license and a permit to sell as mobile food businesses have a lot of regulations. You'd need contacts and contracts with suppliers, and most importantly you'd need a lot of money to pay for your own expenses for the first few months to few years that you aren't profitable.

But I don't disagree that it's impractical for low skill laborers to unionize, at least in an open boarders multiculti "country". If we lived in a proper nation it might be different.