Look at the other people in that place. A guy is stuffing a ballot box right there in the open and no one cares. They even line up and wait until he is finished.
Maybe its insurance policy. :) If the official figures are to believed, turnout in urban centers is low.
Putin will get a much higher turnout in the countryside and small towns.
There is an urban-rural divide in Russia. The Kremlin is resigned to the fact it can’t get people in Moscow and St. Petersburg to be as enthusiastic about the President as elsewhere around the country.