Ages of consent vary and as per Islamic guidelines the local laws should be followed. If a girl can legally get married at X age, then she can also decide to wear a burka as well. In the US 18 is the age of consent, if an 18 yr old girl decides to wear a burka then its her choice.
In the Oakland case, it's not required for the young daughters (depending on their ages) to wear a burka under Islamic guidelines, but then again these are rare examples as you have suggested.
As for the purani Dehli situation, the bearded Mullah and his wives should be following the local law (of India) where the female polling officers should/could demand to see the faces of women when necessary for voting purposes. the fact that they don't even ask, is showing perhaps a bit too much sensitivity.
I don't believe that Muslim women who cover themselves pose a threat to Europe, it is this intolerance which is fueling the fires. Islam in Europe can coexist if given the chance.
Precisely keeping Oakland California case in mind as you have already mentioned that laws in the United States do provide parents pliability to raise their children according to their religious and moral beliefs ----- beside the fact that tattooing and piercing are not religious examples ----- the law does allow children under eighteen years of age to get tattooed and pierced only with consent and supervision of their parents.
As such it should not be considered immoral or unethical for girls under eighteen years of age to wear Burqa with the consent of their parents since the apple does not fall far from the tree.
Nuff said!