> offenders can "buy" points from other people so that they still can drive

It's illegal, some local official already been prisonized for doing that[0]. So the argument is no longer true.

If the "social credit point" will become a reality, then I don't think it can be traded in a lawful fashion as well, as allowing it will discredit the system.

Might be a good way to destroy the system by rending it useless now that I think about it.

[0] https://translate.google.com/translate?sl=zh-CN&tl=en&u=http...