I assume people involved in this sort of activity would convert to Monero first (can be done without KYC in a 100 different places). Then they would go to localmonero or a site like it and select cash in the mail. They would round to the nearest XMR at a time when transacting on localmonero so that even if the exchangers they used were compromised the government wouldn't be able to link them to the initial BTC->XMR swap based on transaction amounts.
Not at this scale. You can do many transactions in the way that you describe and perhaps withdraw a million dollars, but you can't launder a billion dollars this way.
