I’m Finnish, and our “poverty food” is still popular to this day. One of the reasons is that it’s actually very nutritious. Since Finland has been a poor country with lots of famine, wars (mainly Sweden and Russia fighting among themselves about who gets our land) and very little upper class of its own (not much royalty, either), our main dishes have consisted mainly of gruel and dried bread (rye/barley/buckwheat). Some fish and forest berries, too. Milk and sour milk (butter was for export only). Turnips, lots of them (later on replaced by potatoes).
This is all reflected in our modern day cooking: many of us start our day with oatmeal, often accompanied by berries (bilberries being very popular). Rye bread is the most popular bread around, and many adults drink milk daily.
That being out of the way, hernesoppa (“pea soup”) might be one of the most popular poverty foods around here. It’s a thick, hearty soup made with dried peas and a modest amount of ham/other cheap cut from pork. Seasoned with bay leaves, carrots, onions, salt and some mustard. It is absolutely delicious, easy to make and of course, cheap. It also has a ton of vitamin K, fiber and protein.
Ps. If a Finn is broke, they will surely mumble something about having to eat oatmeal for the rest of the month. :P