Cash is unwieldy in large amounts, which is why most authorities don't care about cash transactions. When cash is used at scale for anonymous transactions (e.g., when the US airlifted cargo planes full of cash to Iraq in 2004 to pay government workers without an Iraqi paper trail), it is international news.
If tornado cash were just obscuring transactions that could have conceivably been finalized with cash by private parties (~<$10K USD), I guarantee that no one in authority would give a shit.
> If tornado cash were just obscuring transactions that could have conceivably been finalized with cash by private parties (~<$10K USD)
A 200 euro banknote's dimensions are about 153x77x0.113 mm, if we consider double that thickness (because unless they're brand new, banknotes tend to crumple) we get that 2,253,400 euros will have a volume of 30 liters, which should fit in a backpack. If you wanted to use the more common 50 euro banknote you could fit 615,650 € in 30 liters.
That amount of cash is heavy and difficult to obtain. It's possible, but it's certainly not ergonomic, and in the US, withdrawing $10K+ in cash from a bank will create a paper trail.
The 500 euro note, which would allow you to carry an even larger sum in the same 30 liters, was discontinued because European authorities were concerned about how much the note was being used to facilitate illegal activity: https://www.bis.org/review/r160211e.htm . In the US, all bills with a face value greater than $100 were recalled in 1969 for similar reasons.
You can transport a greater dollar value in the same volume using diamonds or gold, but again, the amount one person can carry is not unlimited.
Both cash and crypto have their downsides when it comes to money laundering. A non-tech savy person might not trust their crypto transactions to remain anonymous or their funds to be safe, because at the end of the day the only way you can be sure of that is if you read and understood the code. For that kind of person the weight of cash is the lesser issue. I've been told that decades ago my dad's uncle would go on trips to Switzerland with bags full of cash.
If tornado cash were just obscuring transactions that could have conceivably been finalized with cash by private parties (~<$10K USD), I guarantee that no one in authority would give a shit.