That’s just editorialization on the source’s part: the facility exists because cursive is legible to humans, but not easy for machines to automatically classify.
There's also plenty of edge cases: letters get wet, they smudge, get torn or folded, and so forth. A postal system that processes 420 million letters a day[1] with a 99% true positive rate on OCR still needs to divert 4.2 million letters for manual review.
This is a common pattern, and why I think AI risk is overstated…unless we suddenly decide to start wholesale writing off the consequences of tail risk.
In other words, AI doesn't have to do anything perfectly to replace a large percentage of the workforce.