[cknight]

As best I can tell, it adds risks which may or may not be a sufficient deterrent - depending on the business.

Once $10k+ cash transactions are banned, questions will be raised over any cash withdrawals that a business makes that are near, at, or over that limit - and possibly over any regular ones that are below the limit but couldn't be easily explained away on other expenses.

For a business to continue the practice you've mentioned, they would need to keep sufficient cash on hand for making such transactions as needed, at all times. So there are all the associated risks of having cash lying around, on top of the risks of being caught.

It can be worked around, but for some businesses I can imagine that the additional loopholes will be considered onerous enough to stop bothering.