your comparison is also a fiction. there is no election where there are multiple candidates on the same side. cornel west is running against biden and trump and jill stein and claudia de la cruz. none of them are on the same side.
"The same side" is only a way to categorize. You can graph each party on a linear scale. Badly, but you can do it. You can make it more accurate by adding a second axis, such as with the PCT. Still bad, but better. And you can keep adding more and more defining characteristics, until you'd end up with and 8d graph or something utterly incomprehensible to humans.
So whether you like it or not, we as humans with our limited minds stick to things like the PCT, with only 2 axis, or in other words, there are sides.
You're taking up issue with semantics. I don't give a flying fuck what you think about there being sides or not. At the end of the day each party holds some amount of agreement with another.
And I agree way more with Biden than Trump, because Trump wants to kill trans people and end democracy. And I'll vote for Biden to prevent that.