Right, a pary of believers. Does not mean the same thing as doing it in public, then taping it and putting it up on youtube or whatever, which has been done. You can do it behind closed doors with a few pious witnesses, in the company of women, as she herself is a woman, which was also not done.
You, me, few guppies, thousands of others can have their own views how to handle "a party of the Believers witness the punishment". How did Prophet PBUH do it? Was it behind closed doors? I believe that was not the case.
What Taliban do, how they do it, why they do it revolves around their show of power, abuse of people's belief etc.