I'm constantly amazed at how much people know about other people's financial circumstances.
I have absolutely no idea how much or how little my friends and acquaintances receive from Centrelink, nor how much they earn. I mean I could probably ballpark their income, but I don't know details.
Obviously the couple in the OP aren't literally on the poverty line, but I often hear 'on the poverty line' or 'on the bread line' used as an expression. I've never assumed any of the people who have used it think they are ACTUALLY on the bread line, just they are saying that they don't happen to have a lot of cash at that particular moment.