Why is evolution hiding?

[Mister Agenda]

A lizard becomes a wingless bird began that evolves a wing why? Did the wing stub make the bird more adaptable to the environment. How did natural selection know in advance that the bird would need wings. the stubs would be useless for maybe over a million years.
Why would a bird evolve wing stubs that are useless?

I think it takes a special kind of blindness to be puzzled at how an incomplete wing would be useful in a world with dozens of species of animals with incomplete wings that allow them to glide various distances...including gliding lizards, gliding fish, and even gliding frogs and snakes. Even a little bit of a wing is better than none if you're doing a lot of leaping, especially in trees.

As for dinosaurs, they had fully-developed arms that gradually became more wing-like. No 'stubs'.