Security measures are open to everybody in the matter of general rules. EU 185/2010 says that if bag is checked as European standard (which USA complies with), it does not have to be re-checked.
Can you imagine how big fuss we would have at airports if transfer loads would have to be re-screened ?
In the UK all transfer bags are rescreened (at least where I work they are) !
And it doesn't cause any fuss at all