Landlord: “Tell me your monthly sales amount.”
Tenant: “No way, this is confidential business information.”
With a little trick, such confidential information can be collected.
Giving certain incentive, customers will queue up and surrender the sales receipts to the concierge of the mall.
Free parking is one of the incentive models. For in-mall spending over certain amount, concierge validates the parking ticket and captures the receipt details. But this is less granular because not every customer comes to the mall with own vehicle.
A more advanced model is to establish royalty membership to earn points per the spending amount in the mall. This is still not accurate because not every customer will join the royalty scheme but more granular than the free parking model.
Then, confidential sales information could be captured from the crowd for analytics.