As a wheelchair user I have had problems with buggy owners refusing to fold buggy and hold the baby. I've been left sitting in the rain because the person won't fold the buggy because "my babies asleep".
I 've seen buggies loaded with groceries and person holding the baby asleep in their arm. Occasionally someone will debus with the buggy to make the space available but it's rare. I know people are normally good and decent so what changes them on the bus?