It should be noted that we're not seeing large russian infantry formations walking around safely while the tanks and other armored vehicles are sitting ducks. Yes, tanks aren't invulnerable, but anti tank missiles are expensive, bulky, and require some advanced training. With advances in technology and western support, Ukraine is fielding more anti-tank weapons than the russians anticipated, but it still is nothing compared to the number of more traditional weapons like machine guns or mortars it could have pulled out of cold war stockpiles. The russians decided to send in mechanized units with minimal to no infantry support because 1) they needed to advance quickly since their logistics could not support a prolonged war, and 2) any russian walking through Ukraine's flat and open terrain without a few inches of armor around them is a dead man. It's Zap Brannigan logic - a Ukrainian squad can only carry a limited number of anti-tank munitions so you just need to keep sending tanks until they reach their kill count and shut down. This turned out to be a bad strategy which mostly has just resulted in lots of destroyed tanks with few strategic gains, but had they done things differently odds are there would just be a lot of dead infantrymen around those destroyed tanks.
As for unmanned tanks, these have been explored time and again but they don't really work well. Truly autonomous tanks are extremely difficult to implement compared to say UAVs because it's very difficult to navigate. Remote control relies on reliable communication which is pretty difficult to achieve, especially if your adversary is being supported by a more technologically advanced superpower. You basically need a tank crew in another armored vehicle very nearby. This armored vehicle is still vulnerable so you're risking soldiers lives and those soldiers are basically doing twice the work operating and maintaining two vehicles instead of one, plus consuming twice the fuel, without doubling the firepower.
> The russians decided to send in mechanized units because...
Because that is their doctrine, the rest is inconsequential. It's how they train to fight, how they are supposed to fight, what they produced to fight.
There is no infantry push in Russia doctrine, it is developed around crossing Europe in debilitating strikes. You push gaps with mechanized units, filtrate deep and leave town behind you, keeping the front moving and causing the enemy line to fragment, while infantryman behind deliver the siege to the cities as needed. It's built around being the aggressor, stocks deep and then consolidate.
What people see happening here it's just their doctrine playing out exactly as written.
It is quite outdated and it's receiving lot of attrition, but still.
I seriously doubt that russia planned this doctrine against ukraine, as this doctrine has lineage back from the soviet union, and they wouldn't plan for a ukraine war - ukraine would have been the staging point - and the doctrine matched the plan to cross the fulda gap as fast as possible irregardless of losses to capture strategic locations. the russian aggression of ukraine is not the war that the soviet doctrine was built for, and the logic for why they pick the doctrine cannot be the logic by which this war is waged, because the loop goes strategy > doctrine > production > training and not the other way around. they always had a mechanized force, it's not something contingent to this war and not even emergent in this century, bmps and btrs are 60s designs.
I can make as concession that their doctrine mutated in the 00s, incorporating parts of the full spectrum warfare system of battle, even if it's a partial adoption since there doesn't appear to be a full loop between the different corps, and it that they aimed at superior firepower integration with other corps. but while the operations are planned and executed in cooperation with differnt systems of weapons but without the flexibility of a closed loop between the infantry advancing and the other supporting weapons system
that russia planned it's doctrine around not being able to support logistic is, well, wrong. their doctrine focus on aggressive pushes to keep enemy weapons systems away from the major cities, which all are westward of it's territory, and aim to push away the front line so that russian defensive lines can advance and have time to intercept whichever threat the enemy launches. they don't have the luxury of oceans, so the idea is push aggressively irregardless of attrition, occupy with reservist and deploy forward defences, because otherwise the cities, along with the infrastructure and factories needed for the war effort would be at risk.
their doctrinal documents are available, btw, so one just need to find a traduction and read it.
> Yes, tanks aren't invulnerable, but anti tank missiles are expensive, bulky, and require some advanced training.
In general, I don't disagree with your post, but even "cheap" RPG-7 (or a more modern, NATO equivalent) would be an effective method of, if nothing else, slowing enemy tanks. In general, "boom wtf was that" is going to stop an advance even if it doesn't kill the tank.
That's only if the RPG hits the tank, which unless you can get pretty close it probably won't. They're useful for urban combat where a person can get close without being noticed, but for an open battlefield you really need a much more advanced guided missile system which can hit targets kilometers away. And even if you are in a circumstance where you can hit a tank with an RPG, there is a pretty big difference between slowing a tank for a few minutes while it evaluates the situation and disabling a tank. Finally, while an RPG is cheap, it's still bulky - each round is about 4 kg. It's not as bulky as a missile but no one is going to carry enough rounds at one time to threaten a coordinated group of armored vehicles, at least not without sacrificing other capabilities.
As for unmanned tanks, these have been explored time and again but they don't really work well. Truly autonomous tanks are extremely difficult to implement compared to say UAVs because it's very difficult to navigate. Remote control relies on reliable communication which is pretty difficult to achieve, especially if your adversary is being supported by a more technologically advanced superpower. You basically need a tank crew in another armored vehicle very nearby. This armored vehicle is still vulnerable so you're risking soldiers lives and those soldiers are basically doing twice the work operating and maintaining two vehicles instead of one, plus consuming twice the fuel, without doubling the firepower.