Drones can fail even against militias without air defences. See the drones downed in Yemen, Syria, Kurdistan etc. Likely because of loss of communication with the drone, but it could be other reasons. The more sorties you have, the more drones you will lose due to technical issues. Look at the number of downed Orlan-10s for example.
Unless Russia has succeeded where every other national drone manufacturer hasn't.
Most of the Russian strikes on targets announced by the Russian MOD seem to be from missile attacks.
That’s a conclusion based on a lot of unsubstantiated assumptions.
Firstly, you are assuming that all crashed drones will be found. That’s clearly not going to be the case here, especially when we are talking about small commercial stuff that both sides are using in large numbers.
Also, it’s noteworthy to stress that in the overwhelming majority of cases, crashes stuff are first discovered by local civilians who both know the area well and have the luxury of time and freedom of movement to come across them. In the Ukraine case, with the lion share of small drones being used on the frontlines, the likelihood of them being discovered is much reduced since most of the civilian population would have fled and those who haven’t wouldn’t be wondering an active battlefield; and because soldiers are probably too busy fighting or taking cover to notice or care about falling UAVs. Even if they did notice one falling, getting to it is potentially going to be difficult and dangerous.
Most commercial drones have a return home feature when contact is lost with the controller, and it’s a feature Orlan-10 also have. That means that even if contact is lost with Orlans, they will either be able to return to their launch points, or will crash in Russian controlled territory where the Ukrainians will not be able to document their loss.
You are also making the assumption that the Russians and Ukrainians are using their drones in the same way, which they are not.
The Russians are showing strike footage from missiles because that’s what they are using for most of the big strategic strikes, for tactical strikes, they use artillery. The Ukrainians don’t have that option, which is why they are reduced to releasing drone footage of tactical strikes against individual vehicles or soldiers.
There is going to be a vast difference in failure and attrition rates of drones from using them for stand-off recon compared to jury-rigging release mechanisms and strapping external loads they were never designed to carry to do poor man UCAV strikes.
You also have to consider the very different detection and AA assets both sides are using.
The Russians are publishing detailed breakdowns of their shootdowns of drones because they are using SAM and other air defence radars to track and engage these drones. The Ukrainians are almost certainly limited to MK1 eyeball for the most case. That means that their ability to detect Russian drones is going to be massively weaker compared to the Russians.
Rather than the Russians not conduction lots of drone operations, it’s more likely that a combination of the Russians using their drones primarily for observation rather than strike, and the lack of effective detection means on the Ukrainian side is creating the false illusion of safety, where the Ukrainians are not even aware that drones are being used against them most of the time.