It all depends on the size of the company and the stupidity of the accounting/purchasing department. The article describes the fraud ranging from modest to sizable. It's not uncommon for many business to have 50k transactions every week. You don't want to go around getting approval for every transaction every day. It's not uncommon for many businesses to have 300k transactions every month.

The business that lost 30m+ I don't understand... It must have been multiple wires over a period of time. They found some vulnerable accountant with the power and just milked them over time.

Not all transactions are created equal. Six figure cash disbursement transactions should require approval.

And any company that has so many six figure cash disbursement transactions that approving them is an administrative burden is the type of company that most needs this kind of control in the first place.

I have seen emails regularly used to approve 9 and 10 figures transactions. But the approval always knew about the transaction, had talked about it with the relevant manager. And often would double check with the manager they trust that everything is in order.

Can you elaborate at all what kind of billion dollar transactions a manager is approving?

Releasing the funds on a loan, issuing a bond, redeeming a bond, etc.