Why is the US DOJ wasting time and money enforcing other countries laws for them? They broke the law in South Africa. Let South Africa handle it.
But also the trading reputation of a country is kinda a common good that individuals can profit by tarnishing, which makes it a prime target for very-valid and probably-a-good-idea regulation of that sort.
It's a good question to ask why Chinese companies are allowed to get business in Africa with bribery, and the US then doesn't allow its companies to compete on a level playing field with China.
Why should the US take a stance at all? Why not let South Africa deal with it? It's not harming the US, is it?
And if they don't operate in the US, it's not the US's business to police something a company that has no presence in it does.
It's very simple and consistent. Americans and American companies are subject to American laws. People and companies who are in America are also subject to American laws. If you are neither American nor in America, you are not.
Nearly every country in the world follows a very similar set of rules regarding jurisdiction.
Your earlier comment justified it being illegal on the grounds that US companies bribing foreign governments is anti-competitive against other US companies that do not do so.
That's an economic justification, not a moral justification. But if we are considering it economically rather than morally then we do have to consider what happens in the case of a foreign country where bribery is common and there are companies other than US companies that are competing there.
In that case not allowing US companies to bribe does indeed level competition among US companies--they all lose equally to non-US companies. Is that actually a better economic outcome than allowing US companies to bribe (and thus compete with foreign companies) in countries where bribery is normal?
That's a complicated question.
It also might be a national security question if we continue heading into a new cold war kind of world. Is it better to have US companies operating in countries the US would like to influence even if those companies have to bribe to do so, or for US companies to stay out and cede influence to companies from countries on the others sides of that cold war?
Actually, no. As a general principle, countries do not pass/enforce laws regarding potential criminal activity that their citizens commit against citizens of other countries while in those other countries.
To take an extreme example, if you murder a citizen of a foreign country while in that foreign country, your home country is generally not going to charge you with murder. If you come back home, they may extradite you to that foreign country at that country's request, since you broke the law there. But because you were in the foreign country and the victim was also foreign, it's not within domestic jurisdiction.
Laws against bribes paid abroad break this rule. And in 2022 it was found that only two countries in the world actively enforce bribery outside their borders -- the US and Switzerland [1].
So no, your assertion that this is how nearly every country in the world operates, is completely false. It's actually a gigantic exception.
(Things operate differently for military forces, war crimes, etc. But we're talking about regular civilian/corporate law here.)
[1] https://us.transparency.org/news/exporting-corruption-2022-s...
This is because the US wants other countries to confidently allow free trade or event privileged relations with it.