I believe we sometimes think, because our culture is so advanced with respect to that of the ancients, that they were somehow mentally deficient. Yet, this cannot be shown to be true. People in ancient times were generally just as intelligent as we are today. Some of the foundational rules governing our math and science are based upon the findings of ancient scholars. There are reasons for our advanced and technologically complicated society, but having a greater intelligence than our ancient ancestors is not one of those reasons.
Many scholars today look at our modern society in order to devise a system whereby they might judge the literate condition of ancient civilizations. Although they may have a tool that might be used for generalization, they cannot know by its use what the literacy rate was for the Jews in the 1st century AD, especially if education at a young age was encouraged by the Jewish leadership. It does not make any difference what modern scholarship speculates what **may** be the general literacy condition of the Roman Empire, because the tools they use are not meant to measure a culture that goes against the norm.
Literacy was always important to Israel. As I said earlier in a previous post, the Jews were to write the laws on such things as their door frames to keep the ways of God in mind. When Gideon was chasing the Midianite kings, he took hold of a Jewish lad and had him write down the names of 77 prominent people of Succoth (Judges 8:14). This would make sense to no one unless childhood education was the norm for the Jewish family
A text dating to cir. 1200 BC was found in Izebet Sartah evidently written by two students. The last line contains all the letters of the Hebrew alphabet. Moreover, another archeological find of an ancient Jewish calendar, which some interpret to prove widespread Jewish literacy was found dating to the 10 century BC in Gezer. Josephus also wrote of how education of children was held in high regard by his people:
“Our principal care of all is this, to educate our children well.” (Against Apion I, section 12)
“The greatest part of mankind are so far from living according to their own laws, that they hardly know them… but for our people, if anybody but asks any one of them about our laws, he will more readily tell them all than he will tell his own name, and this in consequence of our having learned them immediately as soon as ever we became sensible of anything, and of our having them as if engraven on our souls.” (Against Apion II, section 19)
The stoic philosopher Seneca the Younger (5 BC-65 AD), although showing an anti-Semitic bias, also lends credence to what Josephus claimed:
“Meanwhile the customs of this accursed race have gained such influence that they are now received throughout the world. The vanquished have given laws to their victors… The Jews, however, are aware of the origin and meaning of their rites. The greater part of the people (Gentiles) go through a ritual not knowing why they do so.” (Seneca, De Superstitione – emphasis mine).
The problem is none of this fits our modern point of view. Much of what is appreciated today as a proper education was not appreciated in antiquity among the élite. For example,
“What race of men would you call more wretched than traders and shippers? They sail about seeking markets, ill-supplied, dealing with local agents and petty retailers, borrowing at unholy rates and risking their heads.”
“I’ll teach him a trade—a barber’s or auctioneer’s or indeed a lawyer’s, for that’s what the devil alone can take away from him.”
Often (but not entirely so) medical doctors, like Luke of the Gospel, were slaves, hardly a part of the élite of their culture. Nearly all Roman households had slaves. A typical middle class household had about eight or more. The upper-classes had hundreds, sometimes a thousand or more. Caesar had no less than twenty thousand salves. Who were they and what did they do? To be sure some handled the least favored menial tasks of their masters, but often the slaves were trusted stewards, scribes, musicians, geometricians, managers of farms and estates, masters of ships, accountants, and bankers. Literacy was a necessity for these trades.
 Trude Dothan, “In the Days When the Judges Ruled – Research on the Period of the Settlement and the Judges,” Recent Archaeology in the Land of Israel, ed. Herschel Shanks, Biblical Archaeological Society, 1981, 35.
 Philostratus; Life of Apollonius of Tyana 4:32
 Petronius Satyricon 46: A Poor Man Thinking of His Son’s Future.