Why do flat topped, fuller makeup brushes provide more coverage with foundation?

Why do brushes like this, a href="http://www.eyeslipsface.com/studio/brushes/single-brushes/powder_brush" rel="nofollow"http://www.eyeslipsface.com/studio/brush…/a (it's the one labeled powder brush in case the link doesnt work), usually provide more coverage when applying foundation, as opposed to brushes like this, a href="http://www.eyeslipsface.com/minerals/brushes/single-brushes/mineral_foundation_brush?" rel="nofollow"http://www.eyeslipsface.com/minerals/bru…/a