@vikorr,
But in reply to the gist of what I think you were asking:
Polarising politicians tend to:
- attract a more loyal following; and
- motivate more people to go against them
That is to say, I would expect more people to be motivated to 'turn out' to vote against a polarising figure like Trump.
And if my understand regarding how parochially US people align themselves with their party, then I would expect most of the party faithful to adhere to their parties wishes during what are extreme times (being the pandemic, and perhaps the most polarising US president in living memory). That is to say - I would expect more Democrats to mail vote, and more Republicans to show at the ballot box (which my understanding is what each of the parties asked)
That is to say that once again, I see nothing unusual about it panning out that way.
Of course I have only been paying a moderate amount of attention, so if anything I said is wrong, feel free to correct me.