Where did you get the "30%"? Last time I researched, it was much less than that. Even at casual glance now, highest figures seem to be at most 15%.

https://www.piie.com/publications/chapters_preview/381/3iie3...

Gift cards would be the least efficient method here for large amounts, so I guess it would not surprise me it's not used there. No one's gonna go hunting small amounts of gift cards on discount on ebay to launder tens of millions of dollars. But who knows...