Faces have a lot more acceptable variation, and far fewer configurations, that still results in something cohesive. Hands have far fewer acceptable variations and far more extensive positions and configurations that makes consistency difficult to model without specific training data.
Some open, some closed. More variations of flowers from bud to petals than even hands, less positional requirements. So right place, lacking definition.
Faces have a lot more acceptable variation, and far fewer configurations, that still results in something cohesive. Hands have far fewer acceptable variations and far more extensive positions and configurations that makes consistency difficult to model without specific training data.
now explain vaginas
Some open, some closed. More variations of flowers from bud to petals than even hands, less positional requirements. So right place, lacking definition.