The view from the service side of the counter is not omniscient, but it does provide frequent perspective. That perspective, when combined with the attentiveness that's required of a good barista, means you notice things.
You pick up on things about customers that they don't tell you, that they perhaps don't notice themselves. You see them every day, always at the same spot, often at the same time. This is life as a sitcom of sorts, and we're all characters in each others' dramas.
There was a couple that came every day. Both got coffee and would ask for soy milk to put in it. Sometimes, though not often, they would get soy lattes.
Now only one of them comes. For two weeks I haven't seen the other. The one that still comes now orders a coffee and uses half and half, never soy. I notice this and the connection is clear to me, clear as if we'd discussed the whole situation at length; although we've never shared words on anything but the drink order at hand.
It feels voyeuristic, at times. The job gives you a window in to peoples' lives. Sometimes, you see things through that visage, real things that make up real life, things that are not small talk. You say nothing because there is nothing to say. You make the coffee and say "Have a nice day", careful not to mean it too much or too little. You deliver your lines just so, and never get out of character, playing your part as best you can.