TIme to move on from both eBay policies and discussion of offshore clones from China and other venues.
As to why the laws are not strictly enforced, I can answer in large measure...it's because there is insufficient manpower, and it doesn't rise to the top of the pyramid for cases to prosecute. (Bigger fish to fry and all that.)
In years past, I've seen container loads of counterfeit knives seized by Customs Inspectors in Miami who didn't have a clue whether the knives were counterfeit or otherwise, only that the proper documentation for import were not properly prepared, as well as the manifests. I ended up explaining a lot of this to vendors at knife shows who knew I was a federal LEO at the time.
It's the same reason why not every container coming across the border in commerce can be searched and why certain parameters have to be followed to determine whether they will be selected for inspection.
Anyway...that's just a thumbnail sketch of the situation.