The Taliban know no bounds and abide by no rules.
They are frequently masquerading as either Burqua clad women, Afghan Uniformed Police or local uniformed private security contractors. The tactic would have the effect of allowing insurgents to move around more freely during the day. And if they fire at NATO troops, they could bring down a withering response on what is ostensibly a civilian vehicle.
Historically, many insurgencies have used this tactic. By placing innocent civilians between themselves and NATO troops they are using these innocents as human shields.
They hope to bring disrepute to NATO and the Afghan government and nullify our advantages in firepower.