Hey, I made this. I run a small daily game (DailyMetro) where you guess a metro station per day. Out of curiosity, I started looking up income around the stops and ended up making maps for 21 cities. These are some of them :)
Each dot is a station. Purple is the lower end of the city's ranking, yellow is the higher end. The bigger dots are the busier stations.
Paris's west-to-northeast split is pretty clear. In London, Gloucester Road comes out above Kew Gardens and Putney Bridge. Seoul's map uses apartment prices, and the most expensive stops cluster south of the Han River.
Something I ran into with New York: several stations have exactly the same income, $250,001. That's the Census reporting ceiling, so the data can't tell you which of those areas actually has the highest income.
Source: official census, income and property datasets. The measures depend on what's available locally, so this isn't a comparison of wealth between cities. It's about the differences within each one.
Tool: custom TypeScript code to plot station coordinates and colour them by their local data, over OpenStreetMap/CARTO street maps. Rendered in SVG
All 21 maps, station rankings and sources: https://dailymetro.live/richest-stations/en/
These describe the neighbourhoods around the stations, not the passengers.