"[...] zero plastic thrown in a garbage can in the United States enters the North Pacific Subtropical Gyre", in bold letters.
But then later in the article, it admits that about 50% of US plastics (it is unclear whether is all of them or only the ones meant to be recycled) were shipped "to Indonesia and Vietnam, which proceeded to improperly dump over 80% of it."
So, it does go into the ocean in the end, whether the fault of the US or any other country, the point is that your plastic straw has a big chance of finding its way to the sea.