"it's based on greed"
All systems reward greed. The more detached they are from how people naturally behave, the more they reward people who chase the system at the expense of thise who what comes naturally. Capitalism rewards people for fulfilling other's revealed preferences. A democratically-decided social credit system would reward people for doing what the majority says they should do. Both systems would occasionally reward people for anti-social behaviour, and require legislative correction. Of the two, I would prefer the one oriented towards the needs and desires of the individual, not of the collective.
We would like a world where people are more kind. Why not pay people to be kind to you?
- an induced kindness it not desirable, we want a natural kindness
- it's subjective: what one person thinks is kind, another doesn't; how would we write that contract?
- there's a tradeoff: while we value kindness, in many cases others value not being kind more than we value kindness; you would likely have to pay more than you are willing to pay
- transaction costs: while the subjectivity problem might be solved, it would be at great expense, this would probably push the price over the edge where it wasn't already
All these reasons apply equally to inducing kindness with a social credit system. I think the tradeoff problem would likely be ignored. That is, people would be forced to be kind against their wish (being punished for not doing it rather than rewarded for doing it). Suppose I believe that the burden of being constantly forced to be kind would outweigh the advantage of living in a world where everyone is kind all the time. A capitalist system tests this claim, a democratic social credit system ignores it in favour if the will of the majority.