It wasn’t trademarked in the US, so DC had no issue with it until now. (DC probably has trademarked it now, but only in the US)
It wasn’t unusual for this to happen. In the past. General Electric, for instance, couldn’t use their exact name in the UK because there used to be a different General Electric company there (since folded).
You also had trademark trolls that would trademark a US item in multiple countries before the US company did it outside the US.