Transporting millions in cash is risky (either you trust the courier with that and risk their life, or you do it yourself and risk yours), and doing so internationally is extremely challenging and/or expensive. By contrast, doing it digitally is quite easy and fast.
It feels a bit disingenuous to insist the two are the same.
https://en.m.wikipedia.org/wiki/HSBC_Mexico#Money_laundering
Along with Civil Asset forfeiture mentioned by others, there are also:
* Know Your Customer laws,
* mandatory Suspicious Action Reports of all transactions over a certain value,
* anti-Smurfing or anti-Structuring laws that against structuring deposits to be under the threshold of SAR reports,
* a whole host of foreign transaction laws
* and plenty more...
So yes, prosecution of use of cash is very alive and healthy with people getting prosecuted for all of these crimes related to use of cash. And this is before any prosecutions that establish direct use for terrorism or drug cartels.
Not if you have to hire a lawyer to show the Bitcoins which left a violent criminal’s wallet were transferred to you legitimately.