Except that it quite clearly wasn't shot down in Iran. It is almost completely intact from whatever evidence we have with videos. Whether it came down because of some failure or whether the Iranians, as they claim took control of it electronically, it quite clearly wasn't brought down using conventional weapons. We can reasonably assume that the technology to take control of drones electronically is not widely available (even in the unlikely probability that the Iranians did it that way), so Pakistan would still have a problem. Attempting to shoot down armed drones (unlike that in Iran) is likely to beget an immediate response. Not an easy choice.
Two stealth crafts down so far, more to come. The heat signature alone gives away the craft using simple image intensifiers or IR scopes.
P.S. I believe that Iran electronically took over the US drone. Russia & China are probably in the process of inspecting it, & don't be surprised if Pakistan gets to know more about it as well.
It is not that hard to shoot down a drone if you want to.