I always took it as a metaphore talking about the way times have changed over the years. There was a time (at least in the States) when you could go to school, graduate, get a job and live a good life. And people were willing to help each other get there. Now, things are harder to get ("the stars hang out of reach") and there is noone around to help you ("there ain't a ladder on the street"). You're just on your own in the world.