Money from criminal activity needs to be cleaned and most people with this type of money accepts 20-30% transaction costs. Its still chaep since they do not have much alternative!
Drugs, weapons and trafficing generates big sums of money that needs to be put back into the system!
I can see people doing it. There was a big sting operation in Australia last year where the people would go into a casino and spend 1/2 hour inserting money into the machines, then cash out and ask for a check.
But I have a hard time believing its as prevalent as this guy says it is.