The Soviet Union was a harsh regime
""Prior to the dissolution of the Soviet Union and the archival revelations, some historians estimated that the numbers killed by Stalin's regime were 20 million or higher"
"Throughout the history of the Soviet Union, tens of millions of people suffered political repression, which was an instrument of the state since the October Revolution. It culminated during the Stalin era, then declined, but it continued to exist during the "Khrushchev Thaw", followed by increased persecution of Soviet dissidents during the Brezhnev era, and it did not cease to exist until late in Mikhail Gorbachev's rule when it was ended in keeping with his policies of glasnost and perestroika."
The government controlled life so much that they dictated who could go on a 'tour' and when and who they took, from Lyuda's diary ""At first nobody wanted this Zolotaryov, for he is a stranger, but then we all agreed, because you can't refuse" in reference to taking a hiker out of the group and forcing Seymon on them
I believe that this threat of death and imprisonment that hung over the country would have forced anyone involved to tell the official version but I am interested in what others say because it seems I might be the only one considering the consequences of not toeing the official line