Why No Product Images in a Shopping Cart?

For a long time now (especially over this past holiday season), I’ve been noticing that most online shopping sites don’t display product images for items in a shopping cart. Go ahead and do a quick check with Amazon.com or Wal-Mart.com or BestBuy.com …add an item to your cart and check to see if there’s a product image next to it. Nothing. Why is that? Is there a reason for this particular “feature”? I can list any number of reasons why an image should be present, but only a few spring to mind for why it wouldn’t be there…

• Amazon’s never really done it, so other sites just follow their lead.
• The “View Cart” page is one of the most highly trafficked pages on the site and to lessen bandwidth costs, product images aren’t displayed.
• Outdated software doesn’t support showing product images in the shopping cart.

The only one that really makes any sense is number 2. Online shopping sites are among the most popular destinations online, and the “View Cart” page must be viewed thousands and thousands of times per day. I can only imagine what sort of bandwidth that generates and having product images would only increase those costs.

However, from a usability perspective, would showing images be worth the extra bandwidth costs? Some online shopping sites seem to think so (ie, TowerRecords.com and Gap.com), but what about you? Are product images in a shopping cart helpful or unnecessary?