Soyuz 1 (1967) and Soyuz 11 (1971) both ended with fatalities. Four cosmonauts died. The Soviet Union did not hide those fatalities. Here is what best illustrates that: All their names are on the Fallen Astronaut memorial on the Moon, put there during Apollo 15, only a month after Soyuz 11 ended in disaster.

There have been no fatalities on Soyuz flights since Soyuz 11, all fatalities occurred early on. That’s forty years without fatalities, and that’s mostly why Soyuz is so safe and reliable.

Sure, more astronauts died during Space Shuttle missions but the Space Shuttle also brought many more astronauts into space than Soyuz. If you look at the percentage of fatalities Soyuz is only doing marginally better – one more dead cosmonaut and the percentages would be about the same. It’s not so much the raw numbers, it’s the forty years. Soyuz is a mature spacecraft, all the kinks have been worked out, the Space Shuttle was always too complicated to ever really work out the kinks, to ever really be considered safe.