This passage is from The Children's Bach by Helen Garner
Up there under the leafless vine they were talking. Vicki saw their breath. From the angles of their bodies she could tell they were arguing. Dexter was trying to make Elizabeth do something.
‘It’s not my job,’ she said. ‘Why the hell should I?’
‘Because no-one else will,’ said Dexter. ‘Because there’s nothing else. What else is there? Otherwise we’re all just dry leaves blowing down the gutter.’
Vicki got into the car and kept her face against the side window. She saw sour street lights, a house standing in a junk yard: old washing machines, tea-chests, a car with no wheels. Elizabeth sat silent with folded arms. Dexter sang aloud in a foreign language.
Does the dialog in bold mean "Because no one else will do it. Because we have no other choice, what is the other solution? Otherwise we will become just like dry leaves blowing down the poorest region"?
Does "the gutter" here mean "the poorest region"?
Does "sour street lights" mean:
dull looking street lights?
very bright street light which your eyes become tired by looking at them?