Russia doesn't "hide" their casualties, they simply don't care. In WW 2, only members of the Communist Party were recorded as war dead and put in the official record. Lots of soldiers signed up to be members simply for that reason. They didn't give a shit about Communism or the party. They wanted to be remembered if they died.
Today, Putin is smart enough to recruit and draft heavily outside Moscow and Leningrad, the two major, modern cities in Russia. Recruiting backwards rubes from rural areas does nothing for his political position. The troops know they'll get paid, and that there are risks. They're generally fine with that. Putin has no reason to hide casualty rates as the people that count politically aren't the casualties.
That would never work in the US today so don't apply American standards to Russia.