This is an excellent question and the answer is it depends on which subset of Costco customers we're discussing; it isn't one size fits all. Let's start with a background of the demographics of Costco shoppers (2004 research). 85% are affluent or living comfortably and 15% are getting by or poor. For many in the 85% how much they're spending isn't a major concern and your question about alignment with needs is a valid one. But there are many exceptions. Some of that 85% are shall we say “fiscally diligent”. I personally chatted with one woman in Costco (who clearly looked affluent with the fur coat and all, and she had a cart full of stuff) who said "Oh my husband will love this, he's always complaining about how much stuff I've put in the cart and complains we're spending too much and that we don't really need half of it." Does a shopping cart function serve as a sanity check in these situations? We think so. “Gee c'mon Myrtle, look at that, the app says we're on the hook for over $500, do we really need all of this?” Contrast that with the typical scenario of not really knowing and showing up to the cash register and the clerk says “$510.25”. At this point if people are surprised rarely do they don't start removing items. They just pay up. And perhaps fight in the car on the way home? ;-)
Even those who are very penny conscious, those who shop at Costco because the perception is they are saving money, can get carried away with impulse purchases. These are anecdotal but on more than one occasion I've heard conversations in the aisles similar to "Husband: wow look at the price of that. That's way cheaper than at X store." "Wife: yeah but are we going to use all of that before it goes bad?" If it's unclear to the couple whether or not they should purchase it, the app adds an additional data point of “Hey, we really can only afford X dollars here today, and the app says we're already near that total, let's skip it for now”.
And regardless of which demographic you fall into others want to be able to confirm that what gets rung up at the cash register is actually correct. Mistakes still get made, price cards on the display are sometimes at odds with what is in the cash register shows. Having a shopping cart function that details every product and what the price is you're expecting to pay is a great feature for some people. “Wait a minute, that's supposed to be $14.99 not $17.99.”
Lastly, the shopping cart is only 1 of 4 core features that TallyUp provides. The product discovery (new products, sales, seasonal), price and stock notifications and nearby stock search are, in our opinion, all very compelling features.
Many Costco shoppers, myself included (member for 17 years) routinely get carried away in Costco. It's part of what Costco purposefully cultivates - the treasure hunt. (It's why they never label the aisles.) Showing up at the cash register and seeing a $400 or $500 bill, or much more, is not uncommon.
Tracking your spending is easy.
Click add to cart.
Enter the 6 digit Costco code. If it is in the database already, you're done. (We have thousands of products in the db already) If it isn't, you enter the name and price so that the next shopper doesn't have to. All the data is community driven.
For those who aren't concerned with how much they spend, there's also many other features besides the shopping cart.