Amazon is making it far too easy for fraudsters to sell their crap, and (from what I hear) repeatedly: products removed because of counterfeit issues get re-added the next day under some other (or new) product code, or seller ID.
I work in the banking industry. It's not very unusual to discover that a client might be doing something that is suspicious enough to notify law enforcement of it (these notices are mandatory).
But that's the last line of defense. You're supposed to attempt to prevent these situations from happening in the first place, hence there are strict AML/KYC procedures.
If a bank were to open a new account for a client they had banned in the past for other reasons, financial supervisory authorities would bring down the hammer on them so fast and so hard, they'd regret it a thousand times more than whatever business they expected to make with that client.
Amazon's claim that they can't do more against counterfeits than they are already doing now is bullshit. There's an entire industry with decades of experience in that matter that they could turn to. But why would they.