Did you see the video(s) of vote counters calmly shuffling "Yes" votes into "No" piles in the Scottish Referendum a few years back?
There's no need to worry about your votes being tampered by some random bad guys, when the government will tamper with them as they see fit anyway.
Election results are pre-determined by governments. Western governments don't want to be too blatant about rigging elections, because they still serve their intended purpose: To make the masses think they have a say in how they're coerced.
But for example, someone living in North-Korea wouldn't place too much faith in their local elections, for good reason. Then again, Kim probably doesn't bother with holding them.
In a nutshell, elections are meant to keep you believing in the political process. But as you may already have noticed, no matter how fervently you cast your vote, the government just keeps shafting you harder and harder.
That's because a piece of paper dropped into a box has no effect on what the politician you voted for can do, once elected. They're all free to keep shafting you, no matter what they told you before you voted.
It's not magic paper, after all.