I just found out, did anyone else know this?

(I apologize for the rant in advance) So I have been driving for Walmart Sparks for over a year now, and whenever I would get small orders with no tips I would get annoyed with the customer and declined the delivery and I would think about how cheap people are for not tipping. A month ago I got Walmart+ through my phone bill. Today I went to the Walmart closest to my house(3 min drive) to get something that the app showed they have in stock for $30. I get to the store and it's marked for $50. I double checked the app to find out that it's only $30 if you order it online and can have it delivered for free same day because of my Walmart+ membership. I figured that they would just have a Sparks driver deliver it. So I thought to my self well I'll add a tip for the driver and still pay less than getting from the store. But while I was checking out on the app it wouldn't give me the option to tip. So this whole time I've been annoyed with the customer when it's been Walmart all along for not offering the option to tip.🤦🏻I feel like a short tempered ass. Anyone else knew that Walmart doesn't always offer the add a tip function?