The answer is actually simple. When an artist releases singles, he tries to pick the songs that would advertise his album... The best ones. The singles are the ones that end up on the radio. The ones that everyone hears. If he picked crappy songs, people would not want to buy the album for fear that all the songs would be pure crap. For this reason, he picks the best songs to advertise.

Granted, not every artist picks the best songs in everyone's opinion. There are plenty of albums on which I like some of the ones no one heard much more than the singles, but that's only my opinion. In general, they pick the best songs to become singles.

And this is why The White Stripes' good songs are their singles.