It's a not a boy/girl thing, it's an individual kid thing!
My oldest started putting his socks on when he was barely two. He put sandals on shortly thereafter and really loved the independence. He continues to be "old" for his age and independent.
His little brother is less than a month from his FOURTH birthday and just decided that he should probably figure out how to get dressed by himself. It's literally been 3 days. I worked on it with him for months, but he just wasn't interested. However, it wasn't wasted time, because when he finally decided to do it, he knew the tricks I'd taught him. I admit, I'm ecstatic that he now changes himself out of his pull-up (he's slow on the potty training, too) and into underwear, pants, shirt, socks, and shoes all by himself while I'm not even in the room! (I still set out his clothes for him)
It'll happen. In the meantime, get him cheap $5 fake crocs! Almost any kid can put those on.