You’re still not getting it. He’s not asking HOW to launder money, he’s asking WHY that line is there. And it’s there as a way to tax federally illegal revenues.

Things like casinos and brothels have historically fallen under this category. I’m sure marijuana could too, if you want to be able to receive digital payments (which is why a lot of dispensaries are cash only).

Also that’s not how money laundering works, if you’re receiving payments like that the cash would have to be laundered before then.