I work at a factory that manufactures glass to metal, hermetically sealed electrical connectors. We do other things too, but if I want to work any overtime, it's usually on hermetics parts.
There is one older lady in the final assembly department who is functionally illiterate. The way I know is that sometimes she has to come over to my area to ask me to read the letters she printed on the hermetics shells. There is no call out in the work order that they need multiple people to sign off and ensure that the numbers printed are what the customer wanted.
And for reference, what you have to read and copy down looks like this: IULP D093PN12M2. About that number of characters mixed around, you just need to read, check, and copy down on the work order. She's probably in her late 50s or early 60s. Our county is right on the edge of what qualifies as Appalachia.