It's not exactly that people are idiots. It's more that some tasks are intuitive, some tasks are trained, and other tasks are counter-intuitive or counter to prior training.

Canonical example: how many doors have you seen with a "push" or "pull" sign on them? If you have to explain it, you've already failed. If a door is a "push" door, then you shouldn't have a pull handle on it!

Car nerd example: recent BMWs have been dorking with the turn signal indicator. Rather than what we all know and love, where the turn signal physically locks up/down until you turn the wheel, they've been doing it all in software. Guess what? People will get it wrong because it's just weird and different.

Now, let's take North Carolina's unique rule that "straight ticket" voting doesn't apply to the presidential race. This is giving both parties fits, since they now feel the need to generate instructions for voters ("vote straight ticket then vote for our guy for president"). Those same instructions, once they cross the border to a different state with different rules, are now a recipe for getting voters to deselect their presidential candidate preference.

To wrap your brain around the extent of the problem, take off your computer wonk hat and put yourself in the shoes of somebody who's never touched a computer beforehand. How are you supposed to figure out whether you've got it right? It's not so simple any more.