Much food is eaten where the source is not known. Schools, hospitals, restaurants, airlines etc. If you wish to eat meat that you know the source of then it rules out many of these places I suppose.
The source in the UK is producers who are supposed to conform to the EU standards which, if they come from outside the UK, have to be conformed with as part of our trade deals with them. We can eat our meat with confidence that it conforms to those standards and that, if any rogue producers are traced they can be sanctioned for nonconformity to the standards. The US are asking , no, demanding, that these standards to be dropped as part of any trade deal with them.
Will the penny never drop?
Those of us who can afford to will buy chicken labelled from a trusted source.
I'm sure you don't mean to sound smug, Ug, but this does come over rather badly...