Companies will often sign shelf-space and display agreements with supermarkets when it comes to displaying their brands' products in-store. There very well might be an agreement between Safeway and Nabisco when it comes to their inventory display.
[1] https://www.thedailymeal.com/eat/triscuit-flavors-how-many-a...
If a potential new customer doesn't like popular Triscuits flavors, but sees a newer but a less popular flavor, the availability and visibility of the less popular but still desirable flavors might convert them into a customer.
...this is exactly the situation I'm complaining about, except that the customer prefers Popular Flavor #3, which the store doesn't stock, to Unpopular Flavor #5, which it does.