The more offenses someone commits, the more likely they'll make a mistake committing one of them and get caught. Yeah most money launderers will have no moral qualms about lying on a form, but someone already on the fence might be dissuaded if the risk of getting convicted increases.
Or even if consciously criminal then one would want to minimize risk of getting discovered.
If the criminals risk forfeiting their money they may look to other avenues instead of using American shell companies.
I very much doubt anyone is under the illusion that this will stop criminals trying to launder money through American companies, it just makes it easier to seize assets of potential laundering operations and to investigate sources.
Also, finding an attorney that is willing to lie, is very easy. How do you think all this stuff is already happening illegally now? ;)
And how this is done - check the provided information against a known-good database (there are plenty of services that you can pay for here). Perform random spot checks. Make sure that the UBO is filing taxes for this entity’s earnings. Etc.
I’m not claiming it’s perfect; fraud detection is a hard problem, and it’s also pretty obscure if you haven’t had to deal with it at your own company.
Note that American compliance is de-centralised. A $5+ million entity attracts a different level of scrutiny from banks, corporate registers and brokers than a no-revenue entity with an overseas signatory.
[1] https://knowledgehub.transparency.org/assets/uploads/helpdes...
[2] https://open.cmi.no/cmi-xmlui/bitstream/handle/11250/2475354...
[3] https://www.jstor.org/stable/90012622