We never learn. But it is clear that the speaker feels betrayed by someone or something, and questions why this has happened to him after all his hard work:
Why should I be standing in line/Just waiting for bread?
The listener is also meant to question it. It was during the Great Depression, and especially during the New Deal that followed the situation described in the song, that many Americans began to answer with the idea that — whatever the original cause of the hardship — rugged individualism was no longer enough. They thought that government must step in to rescue people from what were seen as the worst excesses of capitalism.
Even then, the programs of the New Deal that focused on the problems of the worker were not designed to simply give people money for nothing. They were geared toward providing government jobs, with a special focus on building the infrastructure that had been neglected for years. In the song, however, the New Deal has yet to occur, and the protagonist addresses the individual listener rather than government. The request — a dime — is clearly inadequate, especially because it is apparent that most people are strapped for funds themselves and would find it hard to “spare” one. Another message is one of personal closeness rather than distance — that people were all in this thing together in a society of relationships, emphasized by the protagonist addressing the listener not as “sir” “or “mister” but as “brother” and “buddy.”
The protagonist doesn’t want all that much. His needs are modest compared with ours today. He doesn’t live in a McMansion purchased with a subprime mortgage he couldn’t afford. In fact, it’s likely that he’s never owned a home at all. Even before the Depression led to many foreclosures, home ownership rates had remained below the 50% mark until a post-WWII housing boom caused rates to begin to rise steeply, reaching a high of nearly 70% in recent years.
The singer wants work, and he wants food. Our plight could change over time to resemble his more closely — especially if unemployment rises more than it already has — but so far, much of the angst regarding the current recession seems different. It concerns the destruction of the perception of wealth, especially future wealth, and a new fear of the practice of living on credit, which allowed so many people to spend so much more money than they earned. Nowadays, the lyrics would be more likely to say, They used to tell me I was building a 401(k).
Roosevelt was not above encouraging class warfare, even though he was born to wealth himself. In his first inaugural, for example, he blamed the fat cats in the financial sector:
Practices of the unscrupulous money changers stand indicted in the court of public opinion, rejected by the hearts and minds of men. … Faced by failure of credit they have proposed only the lending of more money. Stripped of the lure of profit by which to induce our people to follow their false leadership, they have resorted to exhortations, pleading tearfully for restored confidence. They know only the rules of a generation of self-seekers. They have no vision, and when there is no vision the people perish.
But that was all in the future when “Brother, Can You Spare a Dime?” was written. We can — and will — argue endlessly about whether the New Deal served mainly to alleviate or to prolong the Great Depression. But one thing is clear: although the welfare state goes unmentioned in the song, it was the government’s answer to the dilemma the song posed. And since then, there’s been little turning back.