Zarrar normally operates in Black... In the last picture, one is a Major and the second is a captain...
The purpose for black uniforms is uniformity, identifying team members to avoid friendly fire, and presenting an organized and disciplined appearance intended to intimidate suspects.
There are advantages and disadvantages with black. Black has been a common color for readily available police equipment (belts, holsters, magazine carriers, boots, etc.). The psychological association for black is apparently one of malevolence and evil, increasing the intimidation factor. The problem with black is the stark contrast with lighter colored backgrounds or well-lit areas that has the potential to make one a visible target.
initially the idea with special operations for hostage rescue or “clearance” work was to conduct these operations at night time or in darkness to give the operators the maximum possible benefit from the environment in which they operate. This is where the black dungarees became the unofficial uniform of many counter terrorism units.
In many operations, with the other side not having much visibility unless they too are using night vision devices, the black dungarees are a cheap and a decent measure for concealment purposes.