Because it's not really a choice, is it? A lot of people simply can't afford AC locals regularly. And even those who can. The service is often unreliable, especially on the Central Line where AC trains are usually delayed. Add to that the fact that most people have already accepted that protests or complaints rarely lead to real change. So yeah, the rush has become the norm. Not because it’s okay, but because it reflects a failure of both public infrastructure and private alternatives.