Srimate Raamanujaye Namaha,
Swamy, i am not sure if this question was asked and if the answer was given in today’s enpani audio 1978, as it is a related topic .. or after hearing that audio is this a new question?
Swamy for some actions , reactions do happen in the same life, which we see sometimes.. so it is not that it will not happen so.. but sometimes the person to be punished may have some punya backlog which will prevent him from getting punished.
Secondly, take a case where one commits a crime at the last year of his life.. and it will take many years to received the effects of that crime, in that case. How is is possible to offer punishment in the same life.. his life cannot be extended for that.
Third case, some punishments can be given only at certain time and age to have similar reaction, so this may happen in future lives.
Also sometimes the reactions of certain actions are so high that it is not possible to pay back in earth, so that is why special places are required. (like special cells in prisons)
There could be many more reasons, which I dont know of..
But we can be sure that Sri Krishna who is the best friend of all , best well wisher of all and the most intelligent of all cannot make a mistake by creating a system which is not perfect.. so from that perspective we can conclude that the existing system is the best..