Ahh but wait, now multiply that dollar figure by 50 customers who tried to buy cauliflower that day. Add 50 more for every subsequent day during which you're still out of cauliflower. Assume they each used to spend $1,000 a month with you, but now they all stay mad at you for 5 months each. After four days you're literally out a million dollars. Though you won't realize that loss until the end of the five months.
If you're out of tunafish too, you don't just lose lovers of cauliflower and tuna, you lose everybody who loves cauliflower, everybody who loves tuna, and everybody who loves both. Unfortunately for you as the grocery store that can't keep the shelves stocked, it's an OR, not an AND, and there is definitely a type of network effect at work.
The costs you incur by having inventory around, and having some of it go bad, are like insurance payments, to avoid the costs you would incur by the much worse problem of losing customers.