The reason is eBay don't really give a **** so long as they get their 20%! Their so called protection schemes I found often just dont work when you really need them.
I have used their so called service in the past and found my self seriously out of pocket both as a seller and a buyer to the tune of $100's.
If you buy internationally eBay seem incapable of coordinating any issues across countries even across Europe.
Well not even that Theogenes. They could have people they hire to investigate the listings. Especially on pricy gear that is well known to be replicated and ripped off in China. Such as Audio gear. Even test the waters by purchasing an item themselves to verify if the item is indeed legit. Holding the money until they verify if the item is indeed genuine. Of course they would make such purchases on items that are clearly fraudulent. It's quite easy to spot them. Usually from the "it's too good to be true prices", shady advertising (misspelling, copied adds as you stated" and of course the location that the items are being sold in. China being a big red flag.