I completely understand the issue regarding employment migration in large areas. It's obvious it happens in a country the size of Australia but it also happens in the UK. For example, the Welsh valleys were highly dependant on mining and when that industry was decimated in the 80s then people moved out to find work. Even now those areas suffer low employment rates, pay is low and it's difficult to find well paying work very close by.
However it is possible to find higher paying work not far from the Welsh valleys. Cardiff is a big city with lots of opportunities. It's not that far. People can, find a job in Cardiff that they don't even have to move away from home for. If anything, the smaller scale of the country allows people to get better paid work without having to relocate hundreds of miles.
The example of the old couple is perhaps true of a time gone by but not true anymore. London is full of people that travel 50, 60, 70 miles into work daily. All the cities bring large numbers of people into them from wide catchment areas.
It's true that the UK has pockets of highly deprived areas and I would agree that the geographic impact is not the same as Australia however for the majority of people they are in areas where low and high income are in relative close proximity. Where population density is similar in Oz (all the major urban areas) then I would say it's very similar as well. The difference is that most people don't have to relocate vast distances to find work.
You will note that my comment was qualified to be discussing urban areas. My observation would be that Sydney and London are very similar in this. You have areas of wealth very close to areas of low income. For example, Grenfell Towers and Holland Park - Sydney CBD and the social housing at Barangaroo (which I know is under threat of "gentrification"). You have housing that has shot up in price over the years to the point where the housing ladder is not accessible for many young people in areas that formally were affordable.
So yes - areas of the NT in Australia (for example) are deprived as are areas of the UK. However it is not true to say that everyone in the north of England is poor. There's plenty of wealth available. Naturally earnings are higher in London but not for those in public sector jobs for example. There is a weighting but not enough to compensate for the bubble. There are plenty of poor people in the south of England.
The comment on debt is very valid and there are many outwardly comfortably off people at high risk should interest rates increase or their credit cards get called in.
Of course, the main point is that the data presented from the Aus census does illustrate a clear difference between JWs and non-JWs. I suspect a similar pattern exists here in the UK.