It makes sense that it is US only if you consider it like a legal experiment to see whether the enormous liability of autonomously entering into contracts or representing a user plus the cost of offering such a service for free is lower than the money you can make from not just selling clicks, but selling the conversion itself.
At that point, you can see that limiting your liability to a single jurisdiction is probably a good idea.
At that point, you can see that limiting your liability to a single jurisdiction is probably a good idea.