I would like you to imagine the following:
You board the 530 afternoon train ,and your baby is sleeping on your shoulder. All the seats are filled. No one in the the train offers you a seat, so you have to carry your sleeping baby on your shoulder for the 45 minutes ride until you get to your stop.
This is true story. It happens everyday and everywhere. I saw this yesterday while I was coming home from work. The parent was a dad and his 2 year old son. I was standing myself, but I would have liked to give him my seat if I had seat.