>If the recycler sells them on ebay as 'never worn ExampleCo jeans' then
the recycler will have undoubtedly violated a contract they have with ExampleCo and will lose in civil court and pay significant penalties greater than the money they made selling never worn ExampleCo jeans and also, undoubtedly, suffer from not having ExampleCo as a customer for their services in the future.
I suspect this will need to be a cultural change. If ExampleCo does it but not RandomCo, of course your reputation will suffer. But if the law is for all of EU, it gives everyone an equal footing.
Then this will be the pressure that is needed for the company's quality assurance to be improved.