Because too many people whine about it without doing anything useful, like using the REPORT button on every listing.
All the reporting member gets is a polite note from eBay. Many think this means they are being ignored.
If the reporter puts the offending lisiting on her Watch list, it may suddenly disappear.If the reporter puts the seller on her 'favourite sellers' list, she may find the seller is suddenly Not A Registered User. NARU.
Or of course you could be wrong.