I have also found Siri’s voice recognition for shopping list items lackluster, especially compared to Alexa. I’m guessing it has to do with Amazon having a better model of actual subjects/products due to having a storefront with said items.

It’s really bad when I’m at the store looking at something in my list scratching my head over what “Silicon Matt to sit rock song” is supposed to be without any way to hear what was actually said or give feedback that what Siri did was wrong.