Subsidies are typically negotiated milestones, lets say we can't get the cost down on a product, we can contractually set requirements that will have the vendor cut us a check if we hit said requirements.
Lets say we want to sell Samsung TVs and Samsung is being hard on cost, we can have subsidies that say if we sell 10000 units a quarter, they will cut us a check.
They could also come at it a different angle and say if you sell at least 20000 TVs and 50% are Samsung we will give you $X.
Some depts. completely rely on these subsidies to have any profit at all. These can be worth millions of dollars, so obviously you have to have your data backing up your claim that you hit your numbers, you can't just say "Yup, we bought 10,000 TVs and sold them all, and only sold 4000 of your competitors TVs, give us millions of dollars"
Even more direct is SBT or Scan Based Trading. This is basically consignment, we get product in but only pay for it when it sells. These can be anything from DVDs to larger items. As far as I know each day every sale of these products is recorded, because we need to keep accurate counts so we know how much to pay... you can imagine the vendors wanting accurate tracking for product that is sitting in our stores for free.
You also have Vendor Managed Inventory, which can be handled a few ways, where literally someone from the vendor does periodic checks, or some are more sophisticated where they want sales data of all of their products so they can forcast what to ship to our stores.
With IT reductions and the multiple layers of interactions on these types of transactions and making sure that we are compatible with external systems, to me its a heavy risk to assume we can run with a skeleton crew