Why do some Australian adults still have trouble with their reading and writing in the 21st century?

For some it has been an issue of broken schooling due to health issues or family issues or language issues for children of non-English speaking families. For some proportion of adults, it may be an issue of a specific learning disability, sometimes called dyslexia.
Many people who can manage their everyday literacy and numeracy needs quite happily, find they have a problem in certain employment or further study contexts. Literacy in different contexts, such as family or employment, require different sets of literacy skills; it is not the case that having learnt some basic set of literacy skills, you can now deal with any reading and writing tasks. This is the situation for many callers to the Hotline. They may have been offered a promotion which involves literacy demands that they are uncomfortable with, or they may be required to do some workplace training that involves literacy that they are not confident with.
The fact that they need to work on their literacy skills is not because they have a skills deficit but because the requirements of the workplace are becoming increasingly more complex.