In the first Iraq war, the KARI system in Iraq, which was built by Thompson-CSF, had its specifications leaked and the US obtained access to back doors and codes that allowed it to bypass and/or disable much of that system. You need to remember that the US and much of the West had friendly relations with Iraq and provided some infrastructure assistance and military support because Iraq invaded Iran.
No such analogous advantage exists in Iran, which is a much larger country, with better air defenses, and no western contractors ready to provide back doors into systems.
By that same logic that fact that we only lost 1 F-15 in, what, almost 3 weeks of bombing is actually a pretty good sign. Especially when you factor in that the Russians (proven) and Chinese (yet to be proven) are assisting Iran and Iran has been buying and building all of this military infrastructure at the expense of living conditions for its people just for this very attack, only to have almost everything obliterated.
And 3 weeks in to the war and the US is flying refueling tankers to refuel Blackhawks in the very area the F-15 was shot down to recover the pilots (1 so far has been received) should be much more informative than it seems to be.
But sure... the KARI system in Iraq.