Yeah, the reality is when people donate things, it's often from a place of the "good" it can do, and not what an item is worth. So while I agree things in good shape aren't that common, they do happen, as many people donate things "new" or like new because they want others to have things that are nice, even if they are having hard times. Most people don't look up the value of something before donating it, for the simple reasons it's a donation.
Many people donate only because it's something they no longer want or need, which is cool, as it helps people, but that is were you get the bulk of garbage at donation centers or thrift shops. But for anyone who checks these places out, there are gems to be had, as a good amount of people donate things in good condition, because they would like to receive said items in a similar condition.