The literal translation of the title is: the Cradle with wheels.
What audience needs to know is that in the traditional Chinese culture, in particular, Confucianism, having a baby without being married first is not tolerated, even if the kid is adopted (it is honored if you help orphans, but adopting one is a totally a different matter, whether you are married or not). This is why the baby was abandoned and this is why the taxi driver deserves a salute of the highest honor in a society of intolerance, especially when he has neither the wealth nor the social status.