Have in mind that no air defense system of any type is without its faults or challenges on its own. What matters the most is to have a multilayered air defense.
Even with a success rate of 99%, 1% is enough to damage an important target which is why it makes it an inherently difficult task to fully defend a landmass (even more so if it is as huge as KSA) from missiles, drones etc.
You talked about the challenges of Israel (100 times smaller than KSA) in the Golan Heights.
Now compare that with KSA's almost 2000 km long border with Yemen (most of that border is highly mountainous with mountains taller than those found in the Golan which are otherwise some of the tallest in the Levant) and large cross-border settlements (actual cities and not just villages) and it makes it difficult to intercept every single drone/missile/munition.
This is the mountain terrain along much of the Saudi Arabia-Yemen border.
View attachment 861931
View attachment 861934
View attachment 861932
As the conflict in Yemen rages, guards protecting Saudi Arabia's border are on high alert for attacks by Houthi rebels.
www.bbc.com
Almost all of the ballistic missiles in the Houthi arsenal originate from the Yemeni Army depots and Yemen prior to the start of the civil war in 2014, had one of the largest missile arsenals in the region dating back to the USSR. Iran transferred some drone and missile tech but a lot is also the work of Houthis/allied groups themselves. I mean even ISIS and other terrorist groups managed to make their own drones etc. You don't really need sophisticated drones when you can literally throw a stone across to Saudi Arabia from Northern Yemen given the terrain and air defenses will react to it.
If what you said would ever occur, nobody (KSA in this case) would be buying any Israeli weapons anymore. Remember that KSA uses air defense systems from many countries (including their own that they are developing) so they have plenty of alternatives. Buying Israeli battle-proven systems is only a plus for them, I guess. They have nothing to lose on it. if it has occurred or is going to occur, I think that it will never become official until/unless KSA and Israel develop official ties on paper. From recent official Saudi Arabian comments such a recognition can only occur if a two-state solution occurs. So there is that.
Was this system offered to KSA officially?