Some poking around in the NSW Transport Open Data portal reveals how many people enter every Sydney train station on a “typical” day in 2016, 2017 and 2018. We could manipulate those numbers in various ways to estimate total, unique passengers for FY 2017-18 but I’m going to argue that the value as-is serves as a proxy variable for “station busyness”.
When working with spatial data cases, it’s important to differentiate an effect you see because it’s actually unique or interesting versus an effect you see because that’s where all of the people are.