Sometimes, when it comes to analytics, you aren't always able to add code to the site, so you need to find other methods. You may also be trying to save costs, so conventional methods aren't always best. For this situation, we're looking at cart add and remove events.
For example, if we were using SiteCatalyst and wanted to normally check our cart add and remove events, we'd have to add a tracking call to every single button that does these functions. This has potential to do a high amount of click calls -- something that could mean paying much more to Adobe. One client reached out to me asking if there was a way to track these two events when the cart page loaded. They didn't have much ability to edit the code at that point, so tracking cart adds and removes had to be added differently. After some thinking, I came up with a solution that was pretty effective.