That's true. It doesn't mean they are, either. In Washington's case, from my reading, it appears he had no qualms whatsoever about slavery for the first half of his life. It was only later, at the prodding of others, that he began to see the light. Up until that point, his slaves were his property and he dealt with them as such. They were a notch above mules.
I believe that the slaves were the property of his wife, from her first marriage. Washington owned very little of his own. He was more or less, a kept man, who benefited from the wealth of his wife’s first husband, who died.