The idea of a 'breadline' first appeared in a magazine story in the USA in 1900. It referred to poor people queuing up every evening for a drink and some bread issued by a charitable organisation. It came more to the fore about 30 years later, when the American Depression years got going. Then, people 'on the breadline' got soup/stew and bread. Nowadays, it tends just to mean 'very poor' rather than actually, in effect, starving.