That is because if they do it, the allies will come and to protect them. This is just my assumption and I don't know if that will happen in actuality. But that seems to be the more plausible scenario why Russia doesn't do how the US have taken Maduro. And what I think is Russia's intention is to wait Zelensky to just surrender and give up the war so that no more collateral damage will be made or it's the opposite thought that Ukraine's Zelensky is thinking.
If such thing will happen, I think we would seesame scenario like with Maduro. Nothing won't happen, allies isn't going to protect Zelensky. Allies is afraid of escalation. It's same like they're not protecting Ukraine now and they're left alone to fight.
I don't think Russia is that interested in taking over the entire Ukraine, they just want to be in charge of the Russian speaking regions, at least that's what the fight has depicted so far. Besides Putin was willing to negotiate with Zelensky, unlike US, which had the option of negotiating and chose to go into the country and hijack a sitting president anyway. The whole truth is that international law only exists for smaller countries with limited military power! But the big countries can do what they like and get away with it.
I doubt that you can be more wrong. Russia isn't interested in taking over entire Ukraine. Entire maybe not, probably more than half of it and in remaining part they would want to install puppet government.
Putin is willing to negotiate? I'm wondering how because I didn't noticed such intentions from him.
I don't think Russia ever had the intension of capturing the Ukraine president Zelensky which I believe Putin was following some international laws and given a serving president it own cordial respect.
Putin and other ally's had also accused Donald Trump of kidnapping the Venezuela president of Maduro with the strategy he was captured by the US military.
Russia don't even see Zelensky as legitimate president of Ukraine because his term already expired in May 2024 and they're telling that Ukraine have to make new elections. What isn't possible under martial law according to constitution of Ukraine