It is quite probable that these so-called experts of Islam and of the Middle East have confused the basic order of the Qur’an with the style of hijab worn by Muslim women of various ethnic backgrounds.
The requirement of hijab is a Qur’anic command. The basic requirement is that a Muslim woman should cover her head and bosom with a khimar (a head covering), and her body with a jilbab (a loose over-garment). Of course, she can leave her face and hands open.1
When it comes to the style, colour, and material of the khimar and jilbab, each Muslim ethnic group can follow the Qur’anic injunction according to their own cultural background. The variety in styles of implementing the same Qur’anic law is so because Islam is a world religion, it is cannot be confined to one region or tribe or culture.
Therefore you see that the Muslim women in Arabia use ‘abaya; the Persian Muslim women use chador; the Afghani Muslim women use burqa; the Indo-Pakistani Muslim women use niqab or purdah; the Malaysian/Indonesian Muslim women use kerudung; the East African Muslim women use buibui; and now in the West, the Canadian Muslim women use mainstream clothes worn with a bigger scarf over the head and a loose outfit.
Islam is not concerned with the style as long as it fulfills the basic requirement of khimar and jilbab. This is where the religion and culture interact with one another, and therein lies the dynamic aspect of the Islamic shari‘a; and this interaction might have confused some of the so-called experts of Islam who erroneously believe that hijab is a cultural tradition and not a religious requirement.