I am a customer and I have to say I do take into consideration how accurately the shopper shops my list determines the tip I give.
I appreciate the shoppers that use communication to replace or make substitutions, it makes a difference for me.
For example, I shop from Publix. I asked for 2 large popcorn chicken from the deli. When the shopper got to my house, she said they didn't have any popcorn chicken at the counter, so she didn't get any. I asked her, Why didn't you ask them to make more, go do the rest of the shopping, and come back to collect them. She said she "hadn't thought of that and didn't know you could ask them to make stuff"
Another shopper I had last week got several items wrong and I ended being charged almost $20 above my check out price due to her mistakes.
I ordered 1 pound of red seedless grapes. They were approx $3.75 a pound. She purchased a 3.5 lb bag, so I asked her why ? She said they didn't have any 1 lb bags, I asked her why didn't she take 1lb pound worth of grapes out of a larger bag, and purchase just one lb. Which is very normal to do. She just replied with a puzzled look and said she didn't know you could separate the bags. So I ended up pay over $12 for grapes.
There were 4 other items she got wrong, or didn't get the correct amount and I actually asked for a refund of those items.