This is an example of how I see one aspect of kamma. I might be wrong, so I invite any correction.
I have two businesses, one being sewing machine repair. I have a standard full service rate but some jobs are more complex, some less. I was repairing a sewing machine yesterday and came upon a decision that I had to make: how much do I charge this person? Since I’m self employed and can charge what I wish, I could charge what I think is a reasonable amount or increase it some. Sometimes this choice is easy, sometimes it’s a complicated equation and needs some consideration for both my time and expertise and the customers well being.
What occurred to me that if I were to take advantage of the situation and charge too much just to get more money, the customer would likely not even notice. However, if I act out of greed, it springs from a defilement of my mind, greed. There is no being or agency that will hold me accountable and mete out my punishment. Rather, it’s that my mind is defiled and my actions from my corrupted mind continue to hold fast to the roots of craving which naturally produce a continuous thirst for more.
If I continue on this path and don’t come to an end of craving and uproot the defilements of my mind, when my body breaks up at death the craving continues. The delusion and the craving naturally follow to the next life, not by the retribution of some judge sentencing me, but from a continuing thirst of my own making.
If I were to follow the example of the Buddha and completely uproot defilements and purify my mind, I would have no craving to continue trying to fulfill and rebirth would have no purpose.