Sure, you could grow up to be someone, like a surgeon or a pilot, who will be faced with a lot of really important decisions. But even in these high-profile careers, you would have access to help most of the time, when needed. And it would be especially important for you to know when you needed help and seek it out, so you might avoid making a stupid mistake. It would only be in an unusual situation where you would have to make a completely independent decision when you weren't quite sure what to do. But this is why you wouldn't be allowed to perform surgery or fly planes without first amassing lots of knowledge and training and practice specific to these situations. This is different from compulsory schooling because, well, it's not compulsory. Anyone who is in training to be a surgeon or pilot has freely chosen his path, knowing in advance what it will entail, and being free to stop at any point. Any test taken along this path is taken by choice.
Admittedly, there will be some times when all of us will have to make decisions or solve problems without being able to consult a friend, or Google. For example, when driving cars, we have to make decisions that could even mean the difference between living and dying. But I'm pretty sure that what gets me through these times is my experience with and knowledge about driving, and maybe a little bit of luck, and has little to do with how many tests I ever took on unrelated topics.
I was one of those students who did well on tests. Apparently I had a good short-term memory, even for facts I didn't care about. And I did care about grades. That combination made me a strong student. But now, in my post-school life, it looks more like a weakness then a strength. It is a weakness, being afraid to admit to not knowing something. I hate it when I don't know an answer, or when people are talking about something I have never heard of. I expect myself to know everything. Because in the world of school, "I don't know" means you fail. And I almost never failed. The few times I did, it was not acceptable. Now I have to remind myself that it's OK not to know things. I have had to practice saying "I don't know."
But that shouldn't be such a big deal for anyone, because in most real-life situations, it is all right if you don't know all the answers, or even any of the answers. I would even say that you can hope for better results if you can quickly admit that you do not know the answer to a specific question, or the best solution to a problem. Because the best things to know are when you need help and where to go for help. And then you go there. And you ask for help. You are not alone and you don't have to figure things out on your own. Unless you are in school taking a test. Then you're on your own, sorry. You shouldn't even be reading this.
I can't remember the last time, outside of school, when I had to take a test, or even answer one question, where I didn't have time to or wasn't allowed to consult someone else or some technology to help me figure out the answers. So why do we force our children to perform this way on a weekly basis for over a decade of their lives?