I've noticed that when rendering the name of a person from one East Slavic language to another, it's usually changed to the native spelling of the target language. For example, the name "Vladimir Putin" appears as "Volodimir Putin" and "Uladzimir Putsin" on the Ukrainian and Belorussian Wikipedia pages respectively. Similar examples include "Nicholas II" being rendered as "Mikalaj II" and "Mikola II", etc. I'm curious about this practice, since it appears so uniformly in East Slavic languages, and it's so rarely seen elsewhere: in English, we very seldom translate "Mikhail" as "Michael", "Lavrenti" as "Lawrence", "Evgenij" as "Eugene", "Olga" as "Helga", etc. So why do people do this, and how did this start?
I think there are two distinct phenomena here.
One is transliteration or re-spelling. All Slavic languages have phonetic spelling, but different reading rules. This means that to write the pronunciation of certain word they have to re-spell them in their own rules. This happens not only with names but with any borrowed words. Slavic languages do not tolerate words spelled not in accordance with their reading and spelling rules, unlike English.
This way Владимир becomes Уладзі́мір in Belorussian.
The other phenomenon is translating certain familiar names from one language to another. This way Николай becomes Микола.