Ukraine's capabilities in that domain are plausibly far more advanced that America's.
Also - costs, casualties, & collateral damage may be far more acceptable in an active war zone, and against drones which are busy killing people & destroying valuables whenever they are not shot down.
Ukraine's capabilities mostly consist of ramming a cheap drone into an expensive one.
This is one of those times when the US has a Maginot Military - massively overpowered against traditional threats, inexperienced when dealing with something like this.
This is not a trivial problem. A cheap drone with a relatively small explosive payload flown into an air intake can take down a military aircraft and cause serious problems for an airliner or private jet.
An airfield is the ideal place to do that, because aircraft are most vulnerable during takeoff and landing.
A few people and a hundred drones launched from a few km away can significantly delay incoming and outgoing flights.
Equip the drones with weapons - or larger explosives - and it's potentially Pearl Harbour.
That's kind of reductive. I know some people who have, uh, relevant experience. The cheap drones are pretty comprehensively engineered and they're complex in the same way that a ballpoint pen is not as trivial to manufacture as it looks.
Shotguns are being used for that purpose. Single buckshot from the top of a AR barrel are in vogue too.
Someone should use a cheap arduino and a mike for aiming and shooting at fpv quadcopters.
I really don't understand why that's not here yet. They can literally convert a toy from github.
They are "being used" but shotguns are the last line of defense. Good luck stopping a little FPV drone with one. If you do not disable it by 50ft you dead. And you have like 10% odds. Way better than 1% odds you might have with a rifle or nothing but...
Jamming is first line of defense, a million times more effective FWIW.
One counter measure is no counter measure. If you look at toys like https://hackaday.com/2023/06/13/arduino-powered-missile-syst... and scale it up with bigger and stronger servo's for holding a shotgun instead of fake missiles; you'll have a second war - with the arms industry. For a bonus you'll also win the war of economy because the bill of materials costs less than a mad maxed FPV drone given you source the shotgun from the land.
Also - costs, casualties, & collateral damage may be far more acceptable in an active war zone, and against drones which are busy killing people & destroying valuables whenever they are not shot down.