Blip has it correctly. Those Captains with half a brain carry an alternate. No big deal in capital cities with another airport close by.
For more remote airports such as Ayers Rock, Karratha, Broome etc the fuel cost differential means you are tankering anyway, so you have a shizenload of fuel over destination.
Just because the employer has a fuel policy doesn't mean the Captain doesn't use his/her head. After all the law requires you to carry "sufficient" fuel for the operation. Thats the Captains responsibility.