Not so - "independents" do stand for the US presidential, though because of varying rules in different states they aren't always on the ballot nationwide. There's a whole horde of them linked below just for 2016:
https://en.wikipedia.org/wiki/Unite...and_independent_presidential_candidates,_2016
They have no hope of winning but can deny victory to someone else. Most famously if Ralph Nader handn't split the Democratic vote in 2000 then Gore would have won comfortably instead of Bush winning (or not winning according to your point of view) by a few hundred disputed votes in Florida. And I venture to say that if that had happened, the world today would be a much less dire place.
Very true, although I was referring to the French Presidential Elections which in the final round of voting only has 2 candidates