The European Union uses something called the Nomenclature of Territorial Units for Statistics (or NUTS) in order to geographically subdivide its member states and collect statistical data. There are three scales: NUTS 1, 2, and 3. And generally speaking, they follow existing administrative boundaries. Or at least that's the goal.
In addition to being used for collecting statistical data, they also form the basis for how the EU implements its " cohesion policies ", which are designed to direct funds toward less developed regions within the Union based on GDP per capita (PPP).
Because these NUTS impact funding allocations and because they can be redrawn if certain criteria are met, there's not surprisingly an incentive to gerrymander. The Pudding has a great visual essay that explains why this happens and how Hungary split its central region into two new ones, isolating its capital, Budapest.
Big cities tend to be, of course, more developed than their surrounding areas. But it is interesting to see by how much. Though an extreme outlier, the Inner London - West region has a GDP per capita that is 625% the EU average (2017 numbers).
Image: The Pudding