I think you will find that a lot of this cheap chicken is reared on factory ships originating from China which hasn't exactly got the best reputation for human rights so it stands to reason their animal rights arent the most stringent in the world! Because the chickens are processed and packaged in UK or Europe (usually Holland), it can have a "produce of EU" label on it
BTW under the mesh that the chicken stand on (all their lives) there is a container full of water containing..... wait for it...........prawns
You can guess what their staple diet is

Sorry going a bit off topic but ultimately its the big supermarkets are to blame.
All this "Fair Trade" should start at home with British Food Producers
Soz guys had to get that off my chest. Im a farmer