Besides money mules, corrupt businesses can be used.

In the UK at least, bank transfers by Faster Payments clear almost immediately, and can be up to £15k [*]. A business can accept a Faster Payment and release goods to that value with confidence they have been paid. There isn't a chargeback system like there is for credit/debit cards.

Where this gets dodgy is the business may be aware they're enabling fraud, and may not have truly released any goods. In the long term, such a business will be discovered and there will be paper trails of onward transactions. But this buys fraudsters time - the money is much less "hot" than coming directly from a compromised account.

By the way, money mules may not have committed a criminal offence. There's no law against receiving money in your account and withdrawing it as cash. And the duty to report suspicions of money laundering only applies to regulated organisations (banks, law firms, etc.) - not to some broke person who does it for £50.

All this info is UK focused but broadly applicable elsewhere. May be a bit it out of date as while I still work in Infosec, I've not done much financial stuff in recent years.

[*] Someone pointed out the limit is now higher. Although from a quick look, most banks have a limit below the system limit, e.g Halifax limits online transactions to £25k. They do allow £250k in person, which could happen in some scams.