My understanding is the chemical wash isn't the inherent issue here. It's the fact that they need to be chemically washed in the first place. Due to factory farming, chickens live in piles of their own poop, and with that comes tons of other unhealthy side effects. To combat that, in the US we simply give them a chemical bath.

The issue at hand is that the EU doesn't want low quality chicken entering the market because it could cause health issues if not cleaned properly, and at the volume we produce, it's likelier than not to be done improperly at some point, at scale. It's just not worth the risk.

But, I could be missing the mark entirely. This is all from memory when I read up on EU food standards a few years ago. My memory of all of these things could be completely off here.