Not speaking English is no longer the issue it used to be, they can see and feel the winds of change as well as we can and they are emboldened. This is NOT to say that conversing with others in a native tongue is bad at all, my Grandmother was the last layer in the Fam to learn Swedish and she and Cousin Ruby spoke it when on the train to work..
They did it cause they thought folks would think they were cool...
I have experienced the ugly side as well, especially in working with Arabs and Asians... They will switch in the middle of something and you can tell from the body language and other things they are hiding something...
The higher you go, the more involved the intrigues get...
I agree it is not that there is anything wrong with talking to fellow travelers in a native tongue. It is just strange given that my gym is one you have to join. That means you live here. It is not that I hear foreign speakers but that I hear SO MANY foreign speakers. I would guess most are Arab.