Explanation: in discworld, seamstress is a euphemism for prostitute, so much that people can't find actual seamstresses.
Happy to be corrected.
Couldn't remember the word tailor, and seamstress felt very outdated and weird, hence the explanation.
Seamstress is still a thing, and different from a tailor AFAIK (probably a lot of overlap)? I have 2 friends for whom that's their job, and they do refer to themselves as seamstresses