I think the challenge is less about the mechanics (reading, writing) and more about the content expressed via these, as there has to be some element of common content as well.
Their criteria is pretty basic “you need to be able to comprehend a 800-word news article”, and we are often failing to meet those standards with alternative education (which isn’t even just homeschooling, parochial systems have issues here too.)
At the end of the day, a service worker needs to be able to read the prices being wrung up on the cash register, and a factory worker should be able to read an instruction manual and safety rules. Not meeting those basic standards basically relegates you to a very small amount of jobs.
I think the challenge is less about the mechanics (reading, writing) and more about the content expressed via these, as there has to be some element of common content as well.