This question is inspired by some UX choices at Groupon which are by design, but seemed odd.
The examples below are the first two items listed here, both right next to each other on the same page.
Certain items can be added to the Cart and there is a Remove button next to the quantity, which one would be required to click if one wanted to remove the item. Here is an example:
For other items, like the next one on the page, there is no Remove option. Here is an example, zooming in on the part with the item list:
On first inquiry, a rep will still tell you to click the missing Remove option.
On second inquiry, (pointing out with screenshot etc. that the option isn't there) they will check and see that it's a different offering; the only option is to purchase the voucher and redeem it.
On third inquiry, they will tell you that you can just click the word Groupon in the upper left which returns to the homepage, leaving and apparently therefore also clearing the cart.
As far as the user can tell, there is no way to know which items would be the remove-by-remove-button kind and which would be the remove-by-clicking-main-logo kind.
However, having these two different procedures for item removal is explicitly by design, the rep says that's by design, and it might even be more costly from a software maintenance perspective to have the difference than be consistent. What are they gaining from this design choice?
Speculative hypothesis (to demonstrate effort): It may be that this is more profitable because few people will reach the third inquiry and most might just feel forced into making a purchase.