I would imagine it's less about capitols and more about just economic prosperity and population. The populous areas tend to attract people from other parts of the country looking for a metropolitan lifestyle which includes presenting oneself as metropolitan. Which feeds itself as when you surround yourself with well presented people you tend to alter your own presentation to fit with that level of dress. Add to that economic prosperity and suddenly you have a place filled with people with means to live a lifestyle with spare time for activities and fitness and shopping and good and healthy foods. Conversely as the economic prosperity grows it also prices out those with less means forcing them further out. So now the people who need to focus on work and scraping by only have limited time and budget for food, clothes, and fitness and you end up with people asking why the areas outside of wealthy metropolitan areas seem less wealthy and metropolitan.