Let's go to Tom's full-paragraph description of the time period of the play:
To begin with, I turn bark time. I reverse it to that quaint period, the thirties, when the huge middle class of America was matriculating in a school for the blind. Their eyes had failed them or they had failed their eyes, and so they were having their fingers pressed forcibly down on the fiery Braille alphabet of a dissolving economy.
Simply put, the American middle class was uninformed, misled and blind, much, sadly to say, as it is today, blind to the world of big business, money and mortgages that was falling apart around it. They were forced to learn hard lessons in the school of surviving on less and less.
Banks were failing, jobs and incomes were lost, and the future looked bleaker and bleaker. And Tom, Amanda, and Laura, like so many folks in America, and indeed in much of world today, were innocent bystanders of a global economic train wreck. Blind, yes, to forces that were beyond their control yet which ruled their meager everyday lives.
Without jobs or a steady income, people went hungry and even the local grocer, Mr. Garfinkel couldn't really afford to let poor Laura have a stick of butter on credit:
LAURA: ...Butter and what else?
AMANDA: Just butter. Tell them to charge it.
LAURA: Mother, they make such faces when I do that.
AMANDA: Sticks and stones can break our bones, but the expression on Mr. Garfinkel's face won't harm us!
Maybe not, but it is a bitter reminder of how very bad off we are.
In Act I, Tom says:
Yes, I have tricks up my pocket, I have things up my sleeve. But I am the opposite of a stage magician. He gives you illusion that has the appearance of truth. I give you truth in the pleasant disguise of illusion. To begin with, I turn back time. I reverse it to that quaint period, the thirties, when the huge middle class of America was matriculating in a school for the blind. Their eyes had failed them, or they had failed their eyes, and so they were having their fingers pressed forcibly down on the fiery Braille alphabet of a dissolving economy. In Spain there was revolution. Here there were disturbances of labor, sometimes pretty violent, in otherwise peaceful cities such as Chicago, Cleveland, Saint Louis . . . . This is the social background of the play.
Tom sets up the play's main theme: truth vs. illusion. He sets his memory play in the Great Depression, where the American middle class could not see much hope in the economic future. They had matriculated from World War I ten years earlier, and were about to matriculate to World War II in the next ten. Not to exaggerate, but hese were perhaps to worst twenty years in the history of the world, not just America.
When authors speak of blindness, it is always metaphorical: it means spiritual blindness. It means people have lost their moral vision; as a result, they become cruel, arrogant, and savage. Blindness is usually reserved for individuals: Oedipus, for example. But to say that a collective people, the majority of Americans were blind, is a bold statement. It reminds me of Jose Saramago's novel Blindness in which all of society turns blind, except for one woman. The social breakdown is sudden and appalling. The blind people live in feces; they form gangs; they rape, steal, and hoard. To have an entire society literally blind is an apocalypse. Tom's statement is not merely to be ironic: I think society in the 1930s and 1940s was indeed on the verge of ending itself.
So, you must ask yourself: is Tom morally blind too? Do we have a play here in which a blind Chorus is leading a blind cast? What's the distinction between truth and illusion if this is the case?