The reasons for these Portuguese heading to Spain are quite simple: they can find higher-paying jobs in Spain, and it's not difficult for Portuguese people to acquire Spanish nationality.
Portuguese can understand Spanish, and there isn't much difference in appearance and cultural disparity between the two sides.
This leads to almost no cost for Portuguese to transform into Spaniards, which is why many Portuguese choose to go to Spain.
Perhaps the Portuguese Government should be thankful that Spain's Extremadura State is a region with a small population and not much industry.
If the positions of France and Portugal were swapped, and Portugal bordered Spain's Catalonia, just one Barcelona Industrial Base would be enough to attract a large influx of Portuguese.
Spain's current per capita income ranks in the upper-middle tier in Europe, higher than Portugal's per capita income.
