Many, many people who are on that level of literacy are in fact working with computers. Ask anyone in L1 tech support what kinds of tickets they get. Many involve people not reading the text directly in front of them.
That sounds highly problematic. Probably why there are so many tech support horror stories. Still, if they can fake it enough to keep that job, then they can fake it enough to adapt to tooling changes. Or wash out and get replaced by another who hopefully understands the tool that their job depends on them using to properly do said job. But again also if the pay is low enough the employer probably doesn't care much about performance anyway.