And gambling, too. Remember in 2013 when all those celebrities got busted for gambling in Macao?
> After getting caught gambling illegally, Shinhwa’s Andy, Boom and Yang Se Hyung received their punishments.
> On November 28, the Seoul Central District Court sentenced Andy, Boom, and Yang Se Hyung to monetary penalties. Andy and Boom must pay 5,000,000 won, while Yang Se Hyung will pay 3,000,000 won.
> The fines were dependent on how much money each person bet. Andy spent 44,000,000 won, Boom 33,000,000 won, and Yang Se Hyung 26,000,000 won.
> The three are all currently pulled out of all schedules and self-reflecting on their actions.
> Meanwhile, Lee Su Geun, Tak Jae Hoon, and Tony An are waiting for their first trial to take place on December 6. They bet more than several hundred million won.
https://web.archive.org/web/20140215040022/http://mwave.inte...
America will prosecute Americans for doing certain things that are illegal inside America outside its borders. As another example, if you take a boat to international waters and kill someone on it, you're going to get arrested and prosecuted when you get home.
America will not arrest or prosecute someone from the UK visiting Thailand as a sex tourist.
In this case, the operator of 4Chan is free to blow off the UK's law. They may wish to account for that in future travel plans, though.
However, if I'm going to break one of their laws that they feel very strongly about, I'm probably not going to travel to the UK. That's just begging for something bad to happen. Why risk it?
So in this case, if you know the US is looking for you, why, oh why, would you travel to the US?
But in any case, this is different, as the US has only declared these activities as illegal in the US. They haven't enacted laws saying you cannot gamble outside the US.
When it comes to antiterrorism stuff, it's a totally different story. If I go to the Middle East and provide money to an organization on the US terrorist list, then yes - I can definitely be prosecuted for it if I enter US jurisdiction. And it goes even further - I don't need to enter their jurisdiction. The US can just have me extradited if there is a treaty.
Moreover, the US government can have you seized and brought to the US without a treaty (or even in violation of a treaty), which may become a diplomatic and/or international legal issue between the US and the state where you were seized, and may subject the agents doung the seizing to personal legal difficulty in that state, but has no bearing on the validity of the criminal process brought against you once they haul you back to the US. See, e.g., U.S. v. Alvarez-Machain, 504 U.S. 655 (1992).
Sovereignty is a big thing in international politics. Countries as a whole are loath to meddle in other countries domestic affairs, even in extreme cases like genocide/ethnic cleansing. Violating weird online protection laws are not the sort of thing a country is going to risk an international incident over.
Sure you can find some examples of countries that violate those norms, but they are the exception not the rule.