That's absurd. Political apathy doesn't just come out of nowhere. Nearly everyone who doesn't vote will tell you it's because both of their realistic options are out to fuck them, and in most locales they're right. Give them something to hang onto, have a candidate that offers them literally anything other than not being the other guy or not actively making things worse, and a whole lot more will bite. You might think they're wrong for having that apathy, but to be completely honest what you think about them doesn't matter. What matters is getting people moving.

The reason they don't campaign like that is obvious: the things the people want are not what the ruling class will allow. It's foolish to think that politicians are simply optimizing for what gives them the best chance of winning. Those sorts of considerations only happen within the bounds of what their backers allow.