Why don't crims use burqas??

Well, it's an obvious point. Except in really cold countries, people are going to stare at you while wearing a balaclava. I know they'll stare at you while in a burqa too, but it's less likely to arouse suspicion (except from anti terrorist people). Why wouldn't you rob a bank in a burqa? You won't be severely noticed until you've already robbed the joint anyways.

Also, Guess Who? would be a challenge in muslim countries!!