Pakistanis living in one part of Pakistan usually never visit another part of Pakistan in their entire lives, so it is quite understandable that young children/adults don't know much about Bangladesh. I am from Gujranwala Pakistan and apart from Lahore, Karachi, Multan, Taxila and Murree, I have never visited any other place in Pakistan. I wouldn't have even visited Multan and Taxila, had I not needed to go there to submit my admission applications in universities there, same with karachi I was there only because of work for few months. So if it was not the media, then peshwar, quetta, larkana don't even exist for me. I have never ever visited even a big neighboring city like Faisalabad which is just 150 Km away from my city and I doubt I will ever visit it unless I have some important "work" or "matter" which demands me going there.
Pakistanis by nature are not interested in knowing about the places other than their current own residential cities. This is also a trend that you will notice on internet too, you will hardly see a pakistani visiting non-pakistani forums of india or bangladesh etc or even commenting under the youtube videos related to india or bangladesh. We just don't have the appetite for this kind of adventurism, might have something to do with our indigenous culture. But I have noticed that "indians" are a whole different species than us, they are very curious about everything related to pakistan and they are always spamming comments sections of pakistan related videos and news articles on youtube and various newspapers, blogs, quora, reddit etc.