A supplier pays it's customer to use it's products? Why not just offer a discount?
Probably because it's easier to contain evidence of a (commercial) brown envelope than a discount.
Lowering prices comes to the attention of numerous lowly functionaries in the customer purchasing department who might leak such information to other customers who may in turn demand equal treatment, whereas brown envelopes can be squirrelled away in the ledgers such that only appropriately corrupt reliable personnel are generally aware of them.
Biting the hand that feeds IT
