Explanation:
For the average person, voting can mean different things depending on their poltical view. So it's not that it doesn't matter but just some people don't care for it as much as other people do. Powerful people in charge try so hard to keep certain people out of it, becomes in the case of the U.S where the voting age is 18 year and older, they decided that anyone under 18 isn't fit to vote and they have a good reason. Usually people under 18, have corrupt poltical views because of social media, their parent's poltical view, their friends, and many other sources. The age of 18 is usually the sign of "freedom" so you have your own thoughts and you basically "own" yourself, you're your own person and so you can vite freely without anyone elses' views corrupting you.
