I can’t tell if they’re trying to refute the point (ie the list being long means that it’s definitionally not being hid) or support (ie the list I made is finite and therefore the corruption is hid).
But I think of it like trying to estimate the size of an iceberg by observing the tip. Just because you know a little bit doesn’t mean you actually know about the scale. And there’s every reason to believe it’s quite extensive given how easily money flows from corrupt countries through USD and US persons and companies (eg the major bank that’s constantly getting fined for laundering terrorist and drug cartel money - either they’re the only ones and they’re making a killing providing this service anyway or they’re the only ones anyone is bothering to investigate, but that business is clearly lucrative to continue to engage in).
There is corruption everywhere. If there is a short list that means that the truth is being hid, or your have way too much police (often both).
As you state, the size of the iceberg cannot be understood by what we can easially observe. While there is corruption in the US, it isn't really much worse than other places that are not known for corruption - though understand that the US has a lot higher population and so it might seem that way. (though often those other places are just hiding truth)
The US also sees a huge amount of wealth directly or indirectly flowing through it. I would say that’s the attraction for illegal activities, less the amount of people.
And I don’t know how small you think the list is, but I suspect it’s quite small because whether you get prosecuted from some corrupt act is pretty random since someone has to notice the corruption and try to investigate. Additionally the recent moves by SCOTUS is to significantly raise the bar for prosecuting corruption. So however you think America is fairing compared to other countries, I’d say America today is allowing once more, more institutionalized corruption than it had in the second half of the 20th century (and America’s history is filled with top-to-bottom corruption).
