Some things to consider though:
- Whipping and flagellation were accepted practice in those days. Washington probably had his white troops, in the Revolutionary War, whipped. Children, working in factories, would be paddled for messing up, the adults would be beat. Cororal punishment was viewed as “par for the course” throughout society. The idea that these sorts of things were reserved for slaves, in those days, is 20th century Hollywood creation.
- I suspect that it’s pretty likely that slaves were not all beaten regularly (nor soldiers, nor factory workers). More likely there were a few problem cases who accounted for 99% of all punishment events, in any case where the owner, factory manager, etc. wasn’t just an asshole. I think it’s unlikely that Washington would have risen through the ranks and been held in such high regard in the military if he hadn’t meted out punishment fairly (in the eyes of his men). So while he may have been more strict than many, that doesn’t mean that it wasn’t a reasonable strictness, nor that his wrath fell where it wasn’t deserved.
- Non-abused, perfectly normal children run away from home. Adults try to pick up and leave their spouse, without warning. Pointing out that some number of slaves, among over a hundred, sought to flee their circumstances is not really all that remarkable. Just because people try to escape a situation they are bound to does not necessarily mean that the situation was all that onerous.
- Some husbands are abusive towards their spouse. Some women marry men who are thieves and bullies. Without knowledge of who the slaves were that were sent to the West Indies, it’s entirely conceivable that these were bad people who were doing bad things. You will see today that we take husbands from their wives and put them into jail, if their crimes deserve it. It breaks up their family, but that’s (theoretically) worth the cost of having those individuals free among the general populace, doing bad things.
This is all not to say that Washington was or had to have been a fair and kindly slave master. Possibly he was horrible to his slaves and indiscriminate in his cruelty. That seems unlikely for someone who freed all of his slaves on his death bed, but certainly I have no good evidence either way.
But a lot of the view that all slaves in all households were abused and tortured by their masters is almost certainly false. The view that slaves were mostly dissatisfied with their lives is probably false. To your average slave, that would just be the life that the world gave them, and they’d live it without thinking too much about other ways of life. For most punishment meted, most of the slaves probably would have understood why it was happening to whoever it was happening, and probably thought it was justified, just as we think it’s justified to send people to jail for several years.
There certainly were slave owners who abused their slaves for no good reason, and others who took advantage of their position (particularly with the lady slaves). And those cases probably served as good cases for abolishing slavery. But there were also probably factory managers who beat on all of their workers indiscriminately, and there are probably bosses in all sorts of industries right up until modern day who take advantage of their position with the ladies beneath them. We didn’t shut down the military, factories, and business in order to end these injustices. We worked on stamping out corporal punishment in our society, giving more voice to those at the bottom, and started sending bad eggs to jail regardless of their position in society. But before that happened, it’s likely that free slaves would have encountered much the same harshness of punishment in the free world as they had when enslaved, and just as often arbitrary as it had been before as well.