The theory (conspiracy or otherwise) that I've heard is that the Russian state looks the other way as long as ransomware makers don't affect Russian systems. So they exclude systems with Russian language keyboard to avoid impacting Russian systems (which might cause the Russian govt to take action against them)

Because they run their operations from there, and don't mess around where they live. Part of their profits pays for protection. Extracting value, and crippling western companies aligns with the strategic goals of these countries. And ransomware is literally a 10B USD business.

Because some countries turn a blind eye to ransomware operators in their territory, and are not targeted in return.