Sounds awesome but doesn't that require the assumption that you would only ever use a car as a grocery transporter?

Sure, but it removes that reason for having a car too. In my life, cars are usually used for: a) Commuting b) Transportation of goods c) Travelling (i.e. entertainment)

Generally, that order reflects what I use a car most for (i.e. Most of the time, my car is for commuting.)

Instacart helps remove the need for transporting goods. Amazon helps remove the rest. And I work at a location that makes commuting via bicycle + public transportation extremely easy.

So I don't need a car to commute or to transport goods. So for the few times that I need a car for entertainment, it doesn't make sense to own one. It makes more sense to rent a car from a local Hertz, or to use ZipCar for those one-off situations.

So Instacart is part of the solution, it isn't the entire solution.

As a fellow urban non-car-owner, groceries or other situations where I need to lug a bunch of stuff are the only remaining obvious situation for me where car ownership offers clear advantages over a bike, transit, or Uber. So to your question, yes, but I don't think that's an unreasonable assumption for a lot of city-dwellers.

How much is the service/delivery charge?

I honestly can't remember, since I'm on Instacart Express, and I get free deliveries above a certain dollar amount, I think $35.

that's fairly irrelevant, i think, since most of the cost comes from the per-item markups.

Oh, there's a per-item markup as well? How big is that?

You can look at Safeway/Trader Joe/Whole Foods prices and compare it to Instacart's to figure that out. That being said, do you ask Safeway/Trader Joe's/Whole Foods what their markup is? The only reason you care is because it's not completely hidden from you.

OTOH, Peapod does grocery delivery around here and just uses the local Stop & Shop's prices, including their weekly specials. I like it since I trust that a major chain will have competitive prices.

that's a very good point.