All that tech, platforms, manpower and literally all the backend data about it (access patterns, descriptions, sales, back accounts, user agents, IPs, everything) and they can't detect something that's blindingly obvious to anyone paying attention?
Even more than that, they require government IDs and other documentation to set up seller accounts, but at the end of the day it's easy to come up with new straw front people for your scam, with clean papers, addresses, and bank accounts.