Show me where it says that.
The official languages of Pakistan are Urdu and English.
Not Pashto, or Sindhi or any regional language.
Most widest spoken language in Pakistan is Puunjabi almost half the country speak some form of it yet still its not official language of country because Pakistan is very divorce country and people need a second language to bridge the gap and that gap is filled by Urdu
And i have no idea why someone will ask this question other than to troll.