Russian style HGV are hard to intercept at their midphase due to their flat trajectory and their capability to maneuever. However, this capability will work only against *large countries* over *long distances*.
For example, if Russia launches such a missile at the US through Europe, it would probably be able to evade air defenses above Europe and the ocean. The US does not know where the missile is heading, so it doesn't know what's the best place to launch an anti-ballistic missile to.
However, if the US intelligence would know the precise location the missile is heading to, for example, Washington D.C, they would know with certainty where to launch the interceptor to and the interceptor would be able to adjust itself and hit the missile, because it is possible to calculate an area which the missile has to go through in order to be able to hit the target. The closer the missile gets to the target, the smaller that area gets. All that's left is to launch an interceptor through that area.
Now, when you're dealing with way wider, generally parabolic trajectories the newer Iranian missiles are using, against a small, short distance known target like Israel, that area the missile has to pass through is small and known. The capability of HGVs to escape air defenses lies within the uncertainty of where the missile is heading to. Once you know where the missile is heading to, you generally know where to fire missiles at, and the missile will make the micro adjustments needed in order to hit the target.