""I just wondered why people can't cope with silence.""
Because as well as social reasons, it's to do with how our brains work (to put it simply.
Some children (and Adults) concentrate and retain information better with background noise and it takes away any anxiety etc. Others do better in silence.
It's the same as putting people in isolation, how we manage is a lot to do with physiological reasons.
Some people live crowds, others have a stress response to be in crowded places.
It can be just a habit as well.
My Mum and my Nan both put their TV on, for company, which was odd in my Mums case, because she didn't like people. My Nan switched hers off for visitors.
My eldest DD puts hers on, to get rid of anxiety, otherwise she's listening for noises, that could mean a break in etc.