Right, so it's important to understand the context in which cash is used.
The vast majority of cash transactions take place in exchange for goods/services rendered immediately. Like I go to a grocery store, buy a pound of bread and pay cash. So disputes are settled right there and then, merchant and customer talk it out. Also, about 90% of cases ticket size is ~20$ so even if a dispute isn't settled in spender's favour it's no big deal. The spender will not transact at the merchant again so in fact more often than not merchants are willing to settle in favour of customers.
Now for larger ticket items I'd hypothesise that 99% of them are done through online through credit-card, bank transfer and what not. Due to safety reasons customer as well as merchant wouldn't want to deal with big sums of physical cash.
That leaves us with suitcase piles of cash being paid; and it's not hard to guess it's mostly being done to avoid authorities. Note that there is a legitimate use case for moving large piles of cash, say casino depositing daily earnings at their local bank. That is not a transaction in a meaningful sense.
I mean, think of all the movie plot points that center around having a drop point for ransom payments. Remember that scene from Mission Impossible - Ghost Protocol in 2011 where they are doing an exchange and the best form of illicit payment is a bag of diamonds.
Not only does crypto make giant illicit ransom payments feasible on a previously unimaginable scale, it's going to make our movies more boring ;)
This is actually a major problem in the U.S. where the fourth amendment is supposed to protect against unreasonable seizure. It is not illegal to carry cash, but federal and local law enforcement agencies will by policy seize cash without charging anyone with a crime. The victim needs to sue to get their money back, and then the agencies use tax-payer dollars to fight it. This is a clear violation of the 4th amendment, but is absolutely rampant.
If we don't fix these problems with cash, you can bet they'll come for your crypto when it becomes popular enough.
