in a real city, you really get a chance to communicate or get to understand one another (sense of touch). In LA, we have a lot of formalities, bureaucracies, and red tape (Metal and glass, like a bank teller booth), this way we really miss real communication/getting to know real people instead of just talking to one another because we have to as one of our daily objectives. Maybe we feel like forceably intervening with because we are desperate to engage, feel, or understand another human being instead of a robot. (We crash into each other, just so we can feel something)
I think it means that people are so afraid to reach out from their boundaries and that many of us are sick of it.
Being enclosed by those self-set boundaries, we've become numb to the feeling of other people or other experiences and when we crash into someone, it reawakens the senses that we never knew we had lost, due to the "metal & glass" which, in my text, means boundary.