It obviously did happen. Most of the prisoners were common criminals, while 1/4–1/3 were political prisoners, like those who sided with and/or fought for Tsar Nicholas II.

What didn’t happen was The Gulag Archipelago, a work of fiction by an anti-communist & anti-Semite[1][2].

During the WWII Nazi invasion, the fatality rate was high, but still lower than in Tsarist Russia. And it wasn’t a life sentence for most. Most people served their term and were released, like almost any other prison system.

The system ended in 1960, while forced prison labor is still enshrined in the US constitution and still happening today.