People are openly selling merch accounts on ebay https://www.ebay.co.uk/itm/APPROVED-MERCH-BY-AMAZON-ACCOUNT-FOR-SALE/253954017992?hash=item3b20d6cac8:m:mtn0Bzb7AA587P7A6AtxIPw:rk:5:pf:0 you can get a fresh account on those private facebook groups for as low as $10. Upon purchasing an account people from unsupported countries use payoneer bank details so that they could be paid. They then go and upload trademarked and copyrighted design and avoid automatic detection by using dashes between their keywords https://www.amazon.com/north-face-hoodie/dp/B07MRKSLRZ/ref=sr_1_41?s=apparel&ie=UTF8&qid=1546639669&sr=1-41&nodeID=7147445011&psd=1
Maybe it's time to start verifying new registrations? Maybe make people submit copies of their ID or copies of their utility bills?