Historically, the price of food was much higher than it is now. Thank our farmers for operating more efficient year after year.
https://mjperry.blogspot.nl/2010/07/as-share-of-income-ameri...
https://mjperry.blogspot.nl/2010/07/as-share-of-income-ameri...
However, it still sounds bizarre that about 90% of their expenses was food.
http://www.hindustantimes.com/interactives/how-do-people-in-...
It may appear for those in state housing that food is their greatest outlay but that would only be if accommodation provided by welfare wasn't classed as "income".
In Twain's position, and time, would food have certainly been the greatest outlay?
For two adults and five children? If you're working class, it'll cost a good chunk even today (barring state subsidies).
What do you think being poor is?