In 16 years of working at a 3PL, I can’t think of a single instance where case sensitivity during the fulfillment of an order was intentional, because humans are not case sensitive.
In my experience, systems transacting EDI would either key based off of GTIN where it doesn’t come up or normalize all SKU input to uppercase text. That entire sentence is meaningless to the average Shopify shop owner, where getting a non-duplicated SKU entered at all is a challenge.
Thank you for pledging to document that SKUs are case sensitive somewhere within the Shopify documentation, where it does not currently exist.