I was disappointed in the propublica article since they usually do very good work.
Amazon always shows the option to see other sellers and even prompts you when there is a lower price that might not have prime shipping.
Most of the time I pay the more expensive price for the following reasons:
1) It is sold by amazon. I know I don't have to worry about the possible issues dealing with third party sellers. 2) The product arrives faster. As a prime member, most items are shipped 2 day. If I look at the other options they are usually 1 week or more out. 3) I trust amazon. This one is the irrational reason due to the fact I could probably save money by looking at a meta shopping engine or ebay. I have a long history as a prime member and trust their pricing and their customer service.
I do think you hit upon something with batching of orders. We rarely buy one off items and typically put things in our cart for an order a couple of times a month. Even then, Amazon offers full transparency. When you revisit your cart, Amazon shows you the price changes and offers to show you lower prices without prime.
Worth noting that Amazon has been regulated (in the UK) over their adverts and use of the term "free shipping".
https://www.asa.org.uk/Rulings/Adjudications/2016/8/Amazon-E...
When I'm not logged in, it shows it has free Prime shipping. When I do log in to my account without Prime, it shows it has free shipping with an order of $49 or more. The only way I can find to see the shipping cost is to add it to my cart and proceed to checkout, which makes it a bit difficult to comparison shop.
> Assuming that that free shipping, unlike Prime, is unconditional, it is worth pointing out that TheHardwareCityCo offers a shipping date from "October 3-12". I'm assuming that you also don't get the return guarantees that you do from Amazon.com.
Amazon also seems to overstate these shipping dates to make Prime shipping look better. Almost every time I have ordered something via a 3rd party like that, it arrives before the earliest date Amazon says it could.
They do that for themselves as well. Their shipping estimates for super saver shipping is always exaggerated, with packages arriving in 2-3 business days rather than 5-7 estimate
In the ProPublica article, the example of Loctite Liquid glue is used:
https://www.amazon.com/gp/offer-listing/B004Y960MU/ref=dp_ol...
The first listing is indeed from Amazon.com as the seller. It has the cheapest price at $5.97 with "FREE Shipping" if you have Prime. So I assume that without Prime, there is a cost for shipping.
The next listing is as the ProPublica article claims, from "TheHardwareCityCo", with a price of $6.75 with free shipping.
Assuming that that free shipping, unlike Prime, is unconditional, it is worth pointing out that TheHardwareCityCo offers a shipping date from "October 3-12". I'm assuming that you also don't get the return guarantees that you do from Amazon.com.
Furthermore, the massive markup cited in Quartz/ProPublica -- $1,400 extra for buying a basket of the 250 most popular products -- only applies if you decided to buy each item individually, as Amazon automatically gives you free shipping (Prime member or not) if you buy $50+ worth of items.
Not seeing the big problem here, to be honest. Frankly, I get annoyed when the default seller for an item is not Amazon, and I have to dig to find the listing that has Amazon as the seller. I have Prime, so that makes a big difference, but I prefer Amazon's reliability over spending time trying to figure out which third-party seller is the least shadiest.