Have you ever entered US as a foreigner? That sounds pretty standard procedure. Even when I was returning with valid visa to my home in San Diego I was asked questions and treated like I was trying to sneak in to the US. Not to mention the 1-2 hour lines in the immigration at Atlanta. The job of the immigration is to check the stories and documentation, if she honestly doubted your story then you wouldn't be let in.
I cannot say anything about Philippines or India, but I know for a fact that UK immigration is closer to US one towards foreigners (non-EU), my wife got once denied visa because she only had 1 month of bank statements prepared instead of 3 months. Often the treatment in other countries is similar to the one the country's citizens receive at your own country, it's called reciprocity and since US is one of the bigger offenders in poor immigration experience around the world the countries treat US citizens poorly as well. So if you are treated badly while travelling around the world it is most likely because you are US citizen.