A few years ago, I worked for a while in a psych hospital.
There was one lady there called Daisy. She was very old, and I used to talk to her when I saw her around. One day she told me that I was one of only two people that said anything other than hello to her.
She'd been living in the hospital for thirty years.
Thirty years of "Hello Daisy", "Hello Daisy", Hello Daisy."
I understood better when I forgot to wear my staff identification badge one day. No one would talk to me. Then when I put it back on, people would look me in the eye again.