How Do We Produce Different results for Same Karma

I am sometimes intrigued by the way we seem to get results for our karma. Some people get punished by God or nature for small mistakes and some seem to do blunders and sin and still seem to enjoy and they are not punished. In my personal life I have seen that I get punished by god for small mistakes and that also instantly. I don't see myself as a perfect person but it's my endeavor to follow the right path as much as I can.
I have discussed this in our family and also thought over this for a long time. One answer that comes to mind is that this is Kaliyuga and honest and sincere people will suffer in this period. But this answer is not acceptable to me. I believe we will always get results for our actions. I also believe that god cares for us so can not be blind to wrongs of some people and punish others for their small sins. I had written this is my last post. So what's the answer?
I believe we all are in various stages of development. Hindu philosophy tells us about mukti and nirvana. That is the stage when we become free form all sins and desires. How do we reach there? -- by continuously improving us. This is not possible in this birth . We are born again and again till we reach this stage.
Now consider an analogy. A baby while playing drops a costly glass item on floor and it breaks with pieces scattered on the floor. The baby starts crying although he/she is unhurt. what do you expect the mother to do? She immediately rushes to the baby, takes the baby in her arms and checks if the bay is hurt in anyway. She is relieved on finding that the baby. The baby is still crying. So she hugs him, kisses him and tells him not to worry about the item. She tells him that she is happy that he is unhurt. Now consider the bay is not a toddler but a 6 year old. He may get severe scolding and if the mother gets very angry a slap or two . If the child is ten , the mother may react first with a slap . So the punishment grows with age and the maturity expected from us. This does not show that mother love son the toddler. She loves her child at all stages but the level of maturity expected is different. she expects her child to grow and develop and is happy when the child shows that.
Now come to our original question. Since we all are in different stages of development. God as our loving father and mother does not expect same level of maturity and righteousness form all.
Accordingly he punishes and rewards us with depending on our level. If we are on a higher level of development he will be more strict with us so that we do not loose the path. The rewards also become less noticeable when we grow. A mother will be overjoyed when the child takes first step . She will hug him, plant kisses and tell everybody about it. But a ten year old shall not expect the same response from the mother whenever he walks. The mother's love has not decreased; now she expects better and higher achievements from him. Similarly god also expects us to achieve greater things as we grow. So we may find someone doing some charity and reaping huge benefits and others doing better work do not get such rewards.
This is my attempt to understand the way the Law of karma works. Your comments and suggestions will be welcome.

Navnit