People naturally like learning some things and dislike learning others. The idea that if some learning is not interesting to everyone is misguided.
And no, something being useful and relevant does not make it interesting on itself. Even if you know it is useful you can just dislike having to learn it.
What is wrong with focusing on what you find interesting and doing only what is really necessary of what you do not? The problem is forcing everyone, regardless of talents or interests or aims, to follow the same curriculum
If you know its useful you are still motived. if you are motivated overall you will develop the discipline to get through what you do not find interesting and put the work in. it avoids situations like this from the first comment in this thread: "they would simply never study or do the homework I assigned them, and then they would do terrible on tests and I'd be stuck having to give them a bad grade."
this is exactly how you create a population that is mathematically illiterate and ripe for manipulation by foreign powers and marketing agencies.
Our society and any democracy relies on a shared minimum level of competence. If you cannot compare costs per unit, do not understand basic biology, or cannot compare evidence, just because it does not interest you, you are cannot function in modern society.
Quite the opposite. A better education overall makes you better at maths, and more able to think critically. Killing kids love of learning is not the way to a better education. Drilling and memorising does not help you learn to think better. Engaging with things you are interested in does.
I find it very frustrating that people just refuse to believe there cannot be a better way to do things despite all the evidence (many, many academic studies) and the experience of people who have tried doing something different.
> If you cannot compare costs per unit
You are missing the point. You can make learning to do these things fun so kids want to do it. They will find a need for basic arithmetic to do something else and learn at that point.
> do not understand basic biology
Why not? Lots of people do not know basic biology after going through the school system.
> or cannot compare evidence
Why would someone who follows interests not be able to compare evidence? Every field has arguments and requires evidence.
For all these, my experience (and the available more formal evidence) is that allowing kids to follow interests (with guidance, help, suggestions as required) leads to far better results than forcing them to sit through a rigid and boring curriculum.