Presented with a choice everyone searches their past for similarity and uses that experience to form a decision. We instantly weigh the benefits to ourselves ( we’re all introspectively selfish ), our family, friends, our wallets, so on and so forth.
I doubt that anyone has this list written anywhere, why would you, it’d be long and to physically check would take longer than the split second we make decisions in. You can imagine this list, perhaps whittle of a few lines as I have already done, so I ask where on this list would ‘the stranger’ come into it?
Some random persona walking about the world minding their own business, you’ll never meet them, if you did they would no longer be a stranger, I mean a complete and forever lasting stranger. Day to day choices won’t affect him ( even what clothes you wear 😉 ) so why would you consider him? Or why would he consider you?
For the sake of humanity is a bit generic so lets be generally specific; a consortium of past events apex at a choice where you’re free to create your own solution. The subsequent avalanche doesn’t affect anyone directly involved with you but there will be an effect.
So in this split second we’ve eliminated consequences to all the people we know I don’t think there is a lot of time left for the imaginary person, perhaps consider whether it would have any permanent effects like death and that’s about it. Yet, they might make all the considerations you would about a mutual friend, or nth degree acquaintance, so they are just like you but they aren’t making the choice.
So if you aren’t giving them much thought and they aren’t giving you much thought why do it? It is a good question, perhaps there isn’t a real answer other than if everyone did the world would be a better place. This is why they call it Karma.