Until 911 we simply lived by the fact that you could obscure monetary flow using shell companies.
With 911 it became crystal clear that this also obscures monetary flow of deadly criminal actors, deadly at scale and deadly at random targets, 911, Madrid, ...
Wouldn't you think that this would change policies and create a push to more transparency of monetary flow?
Currently the policy values the option of tax evasion at scale higher than the option of controlling in the sense of understanding money flow.
Yes you would, and in fact there's been a lot of work done on this and a lot more work to be done. Switzerland has been pushed into radically revising it's financial privacy laws. The era of secret numbered Swiss bank accounts is pretty much over. Many banks have fallen foul of anti-money laundering regulations and fined billions of dollars. It's not great that they violated the rules, but the fact they have been held to account is huge progress.
Nobody can snap their fingers and change how every country in the globe regulates their businesses though. The basic principle of companies owning other companies is too fundamental to abolish, and if you can create one link then you can make chains and these can be complex. There are no magic wands to solve this, so it's going to take perseverance and hard work, and continuing pressure on politicians.
BTW, that's quite a myth. There were never bank accounts where the banks didn't know who the client was. But not everybody at the banks had access to the info what account belonged to which person.
Of course if you as a foreign country could get info about your own citizens having bank accounts is a different question (and that has luckily changed in recent years).
The money flows to the terrorists wasn't through complicated shell companies though, was it? Iirc, they were using the Hawala system of informal banking that relies on family/tribal relationships to quickly transfer funds without leaving traces anywhere Western authorities might see them.
With 911 it became crystal clear that this also obscures monetary flow of deadly criminal actors, deadly at scale and deadly at random targets, 911, Madrid, ...
Wouldn't you think that this would change policies and create a push to more transparency of monetary flow?
Currently the policy values the option of tax evasion at scale higher than the option of controlling in the sense of understanding money flow.