France street harassment: Strasbourg woman attacked 'for wearing skirt'

[SharonClark]

1. "She said more than a dozen people witnessed the incident, but no-one intervened."

"Two of the three men then held her while the third hit her in the face, leaving her with a black eye, she told the station. The men then fled. She said more than a dozen people witnessed the incident, but no-one intervened."
. . .
On Thursday, France Bleu Alsace reported that two women had been attacked in another eastern city, Mulhouse , on Wednesday, after a man told one of them her skirt was "too short"."

This is shocking and disgusting. What is triggering this concern about skirts?