that few people care about, at least in the US
People under the age of 18 can get a job. Part of the money goes to taxes. This money, according to the IRS, keeps you safe while you go to and from your job, pays for the roads and police, as well as safety and security at your job. But you can't vote, and you don't control how much.
In the US, you have to be 18 to vote, but you still get taxed if you're under voting age. Taxation without Representation The government's response is that your parents represent you in elections and in a court of law. But seriously folks, isn't that the retort of colonialists?
There are some flaws here. 1. If you can work, you could probably be tried and held accountable as an adult. 2. If you live in a house with >=3 kids, then you're not being fully represented.
So far, I have yet to see somebody stand up for this. The closest there was to a protest was in the Vietnam War where you could be drafted, but not able to buy beer in most states. (Thanks olmanrvr)