I've been thinking about this too.

I've heard a lot of commentary about how polling has addressed the shortcomings of recent election cycles and that its more or less all fixed now. I do wonder though, there seems to be a heap of things that are very difficult to account for.

For example, who's actually going to vote vs just intending to vote. For example the garbage thing has motivated a lot of people to get it done.

Another is the late break. I think for a lot of people that just don't pay attention to politics, if you ask them 2 weeks ago they just haven't really thought about it - their answers are precooked from last cycle. As the big day comes around and people think about candidates, lots of traditional republicans voters will make a different choice.

Also just generally with polls is the type of person that actually completes polls. Most people ain't got time for that.

Of course I understand pollsters try to control for these things but as these problems stack up its easy to see how there can be some surprises.