[bigjimmyk3]

I can think of a pretty obvious reason why the hard drive wasn't wiped: they didn't know it was there. A normal person processing a pile of donations would probably look at this and think "huh a strangely heavy keyboard," then move on to the next item.

[zirgs]

But why would you donate your hw without wiping it?

[StanislavPetrov]

Maybe the previous owner was deceased and it was gathered in an estate sale? Or left in a storage locker which the owner missed a payment on? There are many reasons!

[Gordonjcp]

That was my first thought. Maybe there are personal photos or messages that someone would like a copy of on it.