Not only is it an excellent way of concealing one's identity, it would be very difficult and very politically incorrect for the police or security men to verify who was inside one.
From The Daily Mail:
I've written about one previous crime of this nature, and some commenters at the Daily Mail article seem to think there have been others.
Police are searching for a burkha-clad man who helped steal designer watches worth £150,000 in an armed robbery today.
The man and two accomplices, armed with a handgun and an axe, burst into Michael Jones Jewellers on the High Street in Banbury, Oxfordshire, at about 2.20pm.
They threatened four members of staff, a man and three women, with their weapons before making off with Rolex, Cartier and Breitling watches.
A man was waiting outside for the three suspects in a black Audi, which was later found abandoned.
Staff at the shop told police the offenders, including the one wearing the burkha, were all male.
The other two were wearing dark clothing and had their faces covered. All are thought to be Asian.
Detective Inspector Steve Duffy, leading the investigation, said: 'Thankfully, nobody was injured during the robbery but obviously the staff have been left very shaken by what has happened.
'The getaway car was found abandoned shortly before 2.45pm in Western Crescent in the Hightown Road area of Banbury.
'I appeal to anyone who was in Banbury town centre today and has any information, however insignificant you think it may be, to contact police immediately.'
No one at the shop, which also has two branches in Northampton, was available for comment this afternoon.
Anyone with information should call Det Insp Duffy via the Thames Valley Police enquiry centre on 0845 8 505 505.
An update from the same article:
The incident is the latest in a spate of 'burqa robberies' where thieves conceal their identity with the full-body garment typically worn by Muslim women.
Last month, a man dressed in a black burqa entered First Choice Travel in Broadwalk, Dunstable, and threatened two female workers with a knife before stealing cash and escaping through the back door.
In a similar robbery this month, a man, again dressed in a black burqa entered Thomson travel shop in George Street, Luton, and threatened female staff with a knife and taking a large amount of cash.
Police have since released CCTV footage of both incidents, which could be linked. However there are differences in the height and build of the burqa-clad thieves.