Russia is just testing our defenses now

Correct, but not in the way you think. Covering everything in air defense (especially against low text/cost) wepons is simply not viable. The actual defense is deterrence, the ability to react offensively (in this case even as part of a big defensive alliance) to an act of war, while protecting only the most critical infrastructure and the stuff used offensively (the latter being the reason air-defense is mobile).

So the actual and very real failure is our cowardly politicians being afraid to call an act of war by its name and react accordingly.

So you didn't do the math... Let's say we go with the 200k per interception of a drone (because there is more than just the spend missiles/fuel but also wear on the jet and a lot of work going into it for just a few hours of use). By above's cost for efficient gun-based systems those 200k get you about 20m of border covered. You would need 13,750 times that money just to cover the small Lithuanian border with Russia (pretending that flying object cannot jsut go around the direct route...).

Sure, you can spend some more money on developing lasers (in fact they do - because that's peanuts spend anyway compared to the actual production costs in numbers) to decrease the cost from ~1000€ for a salvo of smart air-burst ammunition to a fraction of that. Doesn't change the base calculation. It actually only gets worse if those guns are more expensive because of the high energy systems required for each.