Despite how this is being portrayed in some parts of the media this isn't just about head scarves and isn't about being out and about in Tehran itself.
In Tehran it seems AF demanded that their female cabin crew had to wear scarves and full robes to leave their rooms at all..even to walk to the end of the corridor...as the wording of the notice the management put out said:
"outside their room ladies must wear a scarf and a loose fitting garment which disguises their shape".
By contrast (and oddly enough) Saudi seems more liberal since the female crew members can usually move around most public areas of the slip hotel in western dress and without wearing head cover.
There may well be an element of "when in Rome" but fortunately it's all moot now the slip has been made voluntary for females.