I didn't ever say that no one could read, of course business people had to at least be semi-literate, but the VAST majority of lay people...common people were illiterate mostly because they had nothing to read. There sere scribes at that time who would read for you and write correspondence for you if you needed it done.....probably for a price.
The vast majority of *lay* people WERE business people. They had to support themselves somehow and they did it by running their own businesses. Carpenters, fishermen, tax-collectors, tent makers, weavers, whatever.
Plus, it was IMPORTANT to the Jews at least, to be able to read God's word.