Do not be so moronic about some foreigners whom you think cannot understand the words you are speaking because it's English. If you were ask to speak other language and understand their language I know you'll be an idiot because you don't know every word they speak. Pardon me with my Xpression he he he.
Let say you tried to understand and learn mandarin but you wont believe that the Mandarin is different from Fookien and Cantonese and other ethnic dialects being spoken in China. In the Philippines, you think you are fluent in their native language but there are so many hundreds of dialects different from each other from intonation, accent and meaning. What are those dialects anyways from different provinces around the world.
Language and dialects in the Philippines: English, Spanish,Tagalog, Ilocano, Kapangpangan, Panggalatoc, Bicolano, Visaya, Chabacano, Ilongo, Muslim, Taglish, Gaylingo, etc.
If you have anxiety communicating with other people with different language of their own then talk to somebody who can understand your needs. No big deal!
Why not concentrate in one just universal language ? Well, that's the point, every village has its own distinctive culture, heritage, ancient beliefs and superstitious beliefs that they have to follow and abide including their own native tongue. To differentiate themselves from the rest of the world. The usage of universal language is for educational purposes, trade and commercialization, to better distinguish each other from their educational background and employment. Besides, you want to be understood by majority of the population speaking the same language that can be better represent you in such a way to benefit your aim and purpose in life.
It's great to be different. Wag lang sosobra! Pag sobra na Brazil na yun. But Jesus takes no side and He doesn't wear a bra!
Be reminded of the "Tower of Babel."