America's Capitol Is Guarded by Norwegian Surface-to-Air Missiles (2014)

Patriot and S-300 both use "track with missile" guidance that requires close integration between the missile seeker and the radar system. This is ideal for ballistic missile defense where the target is high in the air, but less effective for cruise missile defense where the interception happens close to the ground which interferes with radar and communication signals.

NASAMS, on the other hand, puts the entire tracking mechanism on the missile. The launcher feeds GPS coordinates to the missile to get it close enough to the target that the missile can guide itself there. Instead of requiring a constant target lock that makes the missile's radar system vulnerable, NASAMS can observe the target sporadically and feed coordinates occasionally, which makes NASAMS hard to observe and destroy. Since the missile can find the target autonomously, the radar and launcher could be moved away while the intercept is still in progress.

The S-300/400 missile system has much larger, faster, and longer-ranged missiles, which makes it better against high performance aircraft and ballistic missiles but its high cost magnifies its vulnerability to attack. S-300/400 is so expensive that you can be bankrupted by your enemy destroying them.

Although NASAMS performs less well on paper, in practice putting both the radar transmitter and receiver on the missile makes it highly accurate and able to shoot down targets while expending fewer missiles... Which in turn makes it more cost-effective and competitive against alternatives.