I find that illiterate thing very hard to believe.
SO did I, but it was true. They had to be hired, but instead of working, were first paid regular wage while taking a free Post Office provided remedial reading class, while the position was held open for them.
I believe it. There's a running joke among the deaf that either they are unemployed (on SSI) or working at USPS. Most deaf people are illiterate...
WELL, while I still lived in New York, I had a substitute mail carrier for a few days who was very definitely illiterate. I came down one day while he was putting letters into boxes, and he was holding envelopes up to the front of the mailboxes so he could compare the names on the envelopes to the names on the front of the boxes. Using his finger to go one letter at a time. One box at a time. Through the whole pile and then on to the next box to do the same thing. I didn't want to stand there and wait, so I went back upstairs.
I came back down in an hour and he was still at it.
And there were only seventeen units in my building.
Naturally the mail was a mess. I happened to bring it up, gently, the next day, and he said they normally had him doing something else at the PO, and he was only delivering because our regular lady was in the hospital having surgery.
But I cannot imagine what they had this guy doing, when he literally could not read at all.