Crime and Punishment: the Problem of Proportionality

One of the main principles in criminal law is the proportionality of crime and punishment. Opening every criminal law textbook, one of the main topics which pops up immediately is this proportionality. But to the best of my knowledge there was no study of what really proportionality means. (Of course I am not a criminal law expert and my knowledge about that is quite limited). This proportionality could be studied from many different points of view. From psychology, philosophy, sociology, economics to mathematics!!! Which in my view of one the interesting views should be the psychological one.
Anyhow, to me it seems there is no universal criterion for this proportionality. If there was, the intensity of the punishment to the like crimes in different countries should be the same or at least alike. But it is not. This is an evidence of subjectivity of this proportionality. And it absolutely depends on the anchor points or reference points each society sets in his social norms and code of laws by historical accident or consciously. So it is not enough just to repeat and repeat and emphasize that the crime should be proportional to the punishment, it is also important to embark on the experimental, behavioral and empirical studies to show what these anchor points are.
The importance of this point becomes critical when we take proportionality into fairness and justice consideration. If so, for designing a fair or just or economically optimal criminal system, the perceptions of proportionality in that specific legal system should be studied to find a basis for criminalization. For instance, in some countries, like China, this anchor points are set very high for the economic crimes such as corruption, while in other countries these crimes are responded more gently. As an extreme example, same sex sexual relationships in some countries are not even a crime, while in others responded by capital punishment.
What is clear is the fact that the social norms, religions, ideologies and cultures play a substantial role in creating these reference points. Different historical incidents every society has gone though have significant impact on those points. What encouraged me (a non-expert in criminal studies) to write these few lines was the importance of building models for measuring this proportionality (which is totally context dependent) in different societies by designing experiments and having empirical research on the subject.