So I looked up the specs and found:
- Reapers fly at a "medium" altitude, which is up to about 50,000 feet;
- They can fly up to 300mph;
- Despite being relatively high up they are relatively slow so lots of country have the military capability to shoot them down and have done so. This includes Iran and the Houthis;
- A typical payload is 2x GBU-31 JDAM (1000lb each). The explosive payload is roughly half that but these are relatively cheap (- They will also have 4x AGM-114 Hellfire missiles, which are precision-guided, costs $100k+ each but only has an explosive payload of under 20lb. When people talk about drone assassinations that becccame super-popular in the Obama administration, this is largely what they're talking about;
- You can also skip the JDAMs and just have 8x Hellfires instead.
Now Shahed drones aren't as fast, don't fly as high, aren't as precise and you know they're there (a lot of Hellfire attacks are a surprise). But they're incredibly cheap and they overwhelm missile defences easily just by sheer volume. In fact, we're using $1-4M Patriot interceptors to shoot down $20k drones. Obviously that's not going to scale when Iran can produce thousands a month and the supply lag for Patriots is actually years long. Supplies of certain missile defense munitions are suspected to be critically low already and will take years to replenish.
So where I'm going with all this is that Reapers and Sheheds serve different purposes but however you look at it, a $50M Reaper with $1M+ in munitions is WAY less efficient at deliverying payloads that a swarm of cheap drones, particularly when your enemy has invested a lot in missile defense and your $50M Reaper is vulnerable to air-defense systems from even non-state actors (ie the Houthis).
Put another way, $20k for a 50-100kg payload is incredibly efficient and the US has essentially been forced to evacuate all their Gulf bases because they're completely unable to defend them. Billions in damage has been done to these bases too.
The Reaper just isn't fit for purpose anymore. Use it against a more militarized opponennt (eg Russia, China) and they'll shoot those things down like it was a carnival side show.