China's issue isn't so much the laws / treaties they've agreed to on paper. The issue more the actual implementation and enforcement of said rules.
> Why should India change its policies around sanctions and start implementing them
I'm not saying India has to, they're perfectly within their rights to ignore requests from the US, but neither does the US have to tolerate that (as they have been) - everyone is free to tariff / sanction as much as anyone else (not withstanding other agreements, but the same argument applies to those). In this way, everyone is free to pursue their own actions and ends. And as such, the US and India aren't forced to trade / cooperate outside of their own mutual benefit (i.e. if trade stops being beneficial to the US/India, they should stop).
This is how I mean each country is responsible for it's own outcomes, don't want to deal with the US? Fine. Just don't expect handouts and cooperation from US entities.
What I'm trying to express is that it's a 2 way street and both parties can walk along it as much as they want - and not a moral issue. I'm not saying there's no consequences, merely that it is OK for a country to pursue actions that (it believes) are in it's own favour.
> I'm not sure what you mean by the South Africa example
Completely fair, I've been diving into SA politics at the moment so it's just at the top of my mind. But there's been a long standing degradation in relations, to the point where recently the SA ambassador to the US was rejected by the US because of some very undiplomatic comments he refused to retract - followed by SA not replacing the ambassador for something like 6 months. Meaning there was no formal point of contact between the 2 countries, independent groups and non-ruling political parties tried to bridge the gap but there's only so much they could do. Another similar example is how while every other country tried to negotiate with Trump about his tariffs, SA refused (or forgot) to.