Russia is showing that it has the intelligence reach to target those it wants to target.
It is the same sort of tactic that the US' and its allies uses in its wars on terror, with targetted drone killings.
If they could target specific individuals they definitely would, just like Ukrainian forces killed many high ranking officers (including generals). The fact they don't is just proof they can't.
Note, I do not support Russia in this conflict - I am against all war, including ours! (West) But it is important to not mis-underestimate ones' enemy - and we don't know for sure that they aren't using the drones to target their terrorists - just like the USA has done, essentially every twenty minutes for the last twenty years.
Once again - how do you explain Russia taking worst losses since WW2 and not being able to do anything about it, if they had any capacity to prevent it?
Ukraine will still have an advantage in numbers, but if the war drags on too long they risk losing some political/material support, as the economic war has hit Europe especially hard (US support can/will probably continue indefinitely, though). There have already been many times in the past months when European leaders called for negotiations and ceasefire according to domestic political shifts, so I think this is a big "hidden" danger for UA.
Generally speaking US, and now Ukraine, have precision guided weapons available. Russia doesn’t, because they lack technology.