My two grown daughters order their groceries online and pick them up. My oldest orders everything! Meat, fruit, and veggies included. She is very busy and loves being able to just drive up and them load it in her car. She makes out a menu do the next week and orders everything. I can see it prob wouldn't be the most economical for me. She likes it because she can see how much everything is and a running total of her order. Occasionally, they put in a substitute but they tell her about it. She can also go pick the groceries up between dropping a kid off at practice and be back in time to pick them up.
My youngest daughter has 3 little boys so it's a chore to try to get groceries and shop with them in tow. By ordering online, she doesn't even have to get them out of the car. They both think it's the best thing since indoor plumbing!
I do know that every store doesn't always have some things online that would could possibly get in the store if you went in. By ordering from Walmart she gets her paper goods and toiletries and everything. Things she wouldn't normally buy when she is just buying groceries at HEB