East Asian countries have a long tradition of lacquerware, which is made with urushiol-containing saps. https://en.wikipedia.org/wiki/Lacquerware

In fact urushi is the Japanese word for lacquer, the plant is in the genus Toxicodendron.

Like most jobs until recently, making lacquerware was hereditary, and (clearly) the people making it were able to withstand sustained and direct exposure. It's possible that there is a genetic proclivity involved in ability to do the work, but just as clearly, there is hyposensitivity gained in exposure.

Let me back that up with a citation. https://pubmed.ncbi.nlm.nih.gov/1839723/