We cannot draw any definite conclusions from that I agree, but we can look at the numerous studies that have been done which mostly indicate that the death penalty is not a deterrent. I'm not sure about the life without any chance of parole because of a hostage situation, but much harsher sentences are required for some types of crime.
I'm not arguing in support of the death penalty, but I don't think comparisons with historical eras are very helpful, and many of the studies produce theories which may, or may not, be valid. In any case, deterrence is only one of the theories of punishment, and I suspect that retribution has more resonance for a lot of people.
Do you mean a hostage situation at the point of arrest, inside a prison, or both?