Well to start off, your body is protected by skin, the largest organ in a human body.
But the skin on your hands is much thinner, more delicate, and far more exposed than your face or anywhere else. Can't just grab on to them like you can with your cheeks!
Do they dress up like the rest of your body does?
No...they don't wear those fancy expensive sunglasses for protection that you buy for your face.
They don't get covered up in hats and clothes.
And they don't get any sunscreen on them.
Just left out on their own...by themselves...tired, forgotten, and over-worked.
Not off to a good start already!
Second, they have fewer oil glands, which means the hands dry out faster and stay dry longer.
That means daily handwashing, sanitizers, alcohols, sun damage, cold weather, and even basic tasks like cooking or cleaning all take their toll - in a bad way.