Originally Posted by Baradium

but it also doesn't actually require them to be prompt or otherwise expeditious for us to get to the hotel either. All their job requires is for them to go back to forth. Your tip is what encourages them to either be there when you arrive or get there as soon as they can once you do.

You can also make all the excuses you want, but it doesn't change how you are viewed when you stiff the van driver.