This has been a problem for years in Portugal too, but lately the number and the amount of stealing has increased dramatically. More like a coordinated organized crime.

Historically this was done mostly by some ethnic groups, I'm not sure if now there other forces or people behind it, as police forces have been more of less sleeping on this since it has been a "country problem" not a "city one" and as it has some ethnicities attached to it, the media also avoids to touch it, so the answer is: most of us don't really know what's going on in a deep way.