It’s well stated in many suttas that human beings are the owners of their kamma and related by their kamma. People with mostly fortunate kamma are said to end up in similar groups.
Kamma from the past or present leads to the experience of pleasure or pain in this life, but that “kamma-debt” is huge… since beginningless time and interacting with so many variables. It’s simplistic to say x leads directly to y, but there’s still a tendency for x to lead to y.
Through many rebirths we’ve all been rich and poor, beautiful and ugly, hell-beings and devas. That’s what should compel us to compassion. We’ve been there before; We wouldn’t wish it on anyone else. What matters is what we do now.
I don’t think it’s different than advising someone that breaking the law will probably land them in jail, and saying that people in jail have most likely broken the law. But, ok, now you’re in jail… what can you do? Train your mind and do what it takes to improve your situation.
If you mistreat others because you think they deserve it, that becomes your dark kamma. Sure, that might not be stated in the same sutta, but it’s in the Canon as a whole, and the Canon can’t just be read in bits and pieces. That gives rise to wrong view.
"When you see someone in a bad way, in distress, you should conclude: ‘In all this long time, we too have undergone the same thing.’ " —SN 15.11