I was surprised to learn that sales reps are often paid monthly commissions based on deals closed instead payments received from deals closed. In these arrangements, companies protect themselves by making sales reps subject to clawback provisions that deduct these commissions from their paychecks if the payment never materializes. As a result, sales reps have a strong incentive to quit after closing a large deal, so that it will much more difficult for the company to get money back from them.
From an outsider's perspective, it seems like it'd be simpler to just wait for payment before distributing commissions. But, because this practice is so prevalent, many sales reps choose to work for companies that pay them when the deal closes rather than when payment is received, which makes sense since they want to get paid as quickly as possible.