Criminal court happens in the country where the crime took place.
Furthermore, court happens in the country, where crime took place.
Civil action happens where the guy sueing you chooses to go to court. Which is usually a) a place in "comfortable" reach for his attorney, but not for yours and b) a place where the complainer expects the best possible outcome.
For US patent and copyright lawsuits, that usually means "Texas" because judges in Texas have a bad reputation for being biased against foreign people and/or companies.
Again, they don't care if it's difficult for you to show. That's your problem, and if you don't show, they'll just rule without hearing you. Don't you think Mr. Gerhard would have said "Huh... what? Who gives a fark... we don't do business in the USA." otherwise, instead of spending millions on a lawsuit in a far away country that he doesn't need to bother about?