Me too - which is ironic in this discussion. Not sure I am too convinced by it, it seems to derive from unfamiliarity with the alphabet. In small children at least familiarity with the alphabet is not the same as being able to read.

I was trained to understand that illiteracy in English means someone that cant read or write, but if it was translated as-is, illiteracy means "iletrado" -> someone "without letters" which in my mother language doesn't mean that someone cant read, but a broader category of people who cant read together with people who have very a poor language understanding and communication skills.

Some illiterate 'iletrado'(for us) in some cases can read, but might not understand it very well.

That might explain why the OP used the given word because in some languages its the definition that defines people who cant read.

It's more commonly used in rummage languages, illiteracy is not really used (in the same way that analfabetismo is not used in English)(my swipe keyboard even used the Portuguese version!).

It’s used in many languages, particularly the Romance languages:

Spanish - analfabeto

Portuguese - analfabeto

French - analphabète

Italian - analfabeta

German - Analphabet

Romanian - analfabet

Polish - analfabeta