Instacart errors

I did the math on Costco’s mark up with instacart plus the fee (IC membership?) plus the tip makes me realize people don’t do math. HEB curbside (3% mark up, no fee, no tipping) has been terrific.
This issue has made me really reconsider Costco as I know Sam’s has been very agile. I don’t need delivery, just curbside, which I think would have been great.