And a veil on either side of it

The Rabbi claims that modesty is a function of what is acceptable. But Rashi in Gittin 2: seemingly means otherwise. The Gemara says "and from both sides of it" is a characteristic of a bad person. And Rashi explains and from both sides of it:
"Among the nobles of her hands, like the red-haired women of France, whose flesh is visible from their sides:"
In other words, what was common in France among the Gentiles was to walk around naked below the arms, and yet Rashi perceives this as immodest (a matter pertaining to modesty). It seems to follow from this, according to Rashi, that modesty is not related to what is common in the place, but to the matter itself (whether the flesh is exposed or not).