You are correct that in economic downturns many do go to urban areas. Even in good times most people go to urban areas. I think the US population is now 80% urban/suburban. Rural areas are barely holding their own population-wise and many areas are seeing actual population declines. We’ve had this discussion about young people and immigrants heading to the cities. The key word here is “downturn”. Come a collapse, people will not be going to the cities. Spain has not collapsed. It still has a functioning govt and infrastructure. They are in a downturn and what little economic opportunity exists is going to be found in urban areas.