I think schools HAVE to throw out their old computers. At least they used to. My high school used to do it all of the time. They weren't allowed to give them away or sell them, they had to trash them. I always thought it was a really stupid rule.
They have the same rule in food services. I worked at a cookie store during college. We had to throw away any unsold cookies at the end of the night. They weren't allowed to be given to Goodwill and employees weren't allowed to take any home (yeah right! I got sick of cookies I took so many home. I'd make batches just before closing, just so they'd still be warm when I got them home.

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Does anybody know why these rules exist? I have a few theories, but all in all it still doesn't seem to make much sense and is very wasteful.