What are you suggesting CardiffJaguar? I don't think it would go down very well if people have to be given a test to be allowed to vote. I really don't think that age on its own qualifies people to be better qualified to make important decisions.
There are some young people who are politically very clued up and older people who have spent their whole lives not really bothering, except when some change affects them personally.
The referendum was a classic example. In my opinion, leaving the EU is a disaster. Others disagree. I consider myself quite knowledgeable about the EU and cringed when people came out with provable garbage. One thing I learnt was that there's no point arguing with people whose minds are made up, because they don't listen to reason. Younger people tend to be more open-minded. You sound as though only older votes mattered, but in my opinion, they were the ones who got it wrong.
I would stress that I don't know for certain that leaving the EU is a mistake - maybe I'll be pleasantly surprised. The point is that most younger people will have longer to live with it than I will and they do have the right to an opinion. Beyond a certain age, everybody has the right to make their own mistakes.