I believe it can not easily removed it has to do with the type of skin perhaps? If I pick berries, just one, my fingertips are colored and it remains for days if not weeks. If my children pick them they wash their hands and it's gone. Even if I wear gloves my hands get dirty.
I need to soak in water for hours to look a bit clean. My mother used a steel brush for my knees... Rubbed the skin off...
I wish why it remains. It looks less nice but it is as in the Dutch saying "there are show horses and working horses).
💕