You can say it as often as you like, doesn't make you right. Votes, and the results of them, have consequences. Some of those consequences cause deaths. We left the EU because of a vote. We can debate whether that was a good or bad thing ad nauseum, and people have, but there are clear consequences to that decision. If the Face Eating Leopard party win an election then people are going to get their faces eaten by a leopard. Isn't that going to affect people? Have people not died as a result of a lack of NHS funding? Do government not make polices about stuff like that? You can argue about whether this is a "direct" result, but there's a pretty clear chain of cause and effect there.
My dad's wisdom isn't really relevant to this situation and actually any comparison is a bit irrelevant.I chose those countries because as English speaking countries it’s easier to discern the relative levels of ignorance. But for your Dad’s sage counsel to have any relevance to this situation it would be helpful if you were able to point towards a country which you think is clearly better informed even if just for something to aspire to.
It doesn't matter if we are the most educated, best informed country in the world. The only relevant thing is are we educated and informed enough and, if not, what can we do to improve that. Noting that other countries are worse (I think the US probably are although it's hard to objectively measure this) isn't really relevant. You could get a D in an exam and be top of your class, that doesn't make D a good result.
As I've said multiple times, I'm not saying this is a particularly good idea. I can see issues with it. But sometimes I look at how people vote or people's opinions and can't help thinking "holy shit, there should be a test!". But some of your suggestions as to how to encourage people to inform themselves may be more practical.