Since my comment (parent) is being downvoted, I will elaborate. In the situation under discussion (deletion of a to-do item) a deletion will never free up a significant amount of any resource (e.g., memory). In those cases, it is pretty obvious to me that keeping the data and metadata of the to-do item around so that the user can undelete it is better than popping up an alert.
It got downvoted because HackerNews isn't like Reddit where you comment for the purpose of just speaking your opinion. I learned this the hard way a few times. Unless your comment contributes something to the conversation it's just noise.
A rule of thumb is basically: Unless you have something important to add don't add anything, otherwise it's just more mediocre comments to sort through. That's why HN has good comments and less noise. Whereas at Reddit and forums and comment systems on other sites, everyone and their grandmother chimes in. Creating a monstrous wall of "thank you"s, "neat", "I agree"s and other babble.
