Most of the missile defense systems in the world wasn't tested in real life scenarios.
Israelies were the first to shoot low range missiles, before then, this capability wasn't around.
I can insure u tho, that those missile defense systems passed harsh field trials before went into service, and continue to improve with every day passing.
The latest test of Arrow 3 missile interception, was against Sparrow target missile, which is designed to simulate an improved Shahab 3 missile. The test was a success in 100% according to Israeli and American officials.
David Sling and Arrow 2 are also JV between Israel and USA and keep geting improvements with the latest technology.
Trophy APS was tested again vide wariety of rockets and missiles before it entered service and still get improvements (rumor has it that the next version will include anti kinetic countermeasure).
So u see, the ability to Intercept even low cost low range missiles, is a breakthro, Iron dome keeps gettin upgrades, and
the new upgrades designed to expand and improve performance capabilities of the system.
Besides, even uncostly missile can cause high number of casualties and Iron Dome manage to shoot Hamas made rockets and Iranian made rockets that could get to jerusalem and tel aviv.
Trophy managed to take down Kornet missiles and RPG 29.