They can learn to get up early and commute when they have to do so. I don't think making kids spend 10 years waking up early is necessary to prepare them for getting up early as an adult.
Analogy: they may have to go without food at some point their life, that doesn't mean we have to starve them now so they're prepared. They can learn to do it when they need to do it.
As an aside, if school was preparation for adult life then it really should teach you to drive, cook, and an understanding of the law. There are few things that school teaches that end up being more important than those for adults.
With the alternative frequently being homelessness. It's a lucky few (relatively speaking) who can freely switch jobs and pursue passions.
Most people work simply so they can continue to have a home, food, water, heat...
I don't know about now, but when I was in school (in the US), we were taught all those things and more (a bit of carpentry, metal work, engine repair, simple accounting, etc) YMMV.
While I was not a good student in high school, and basically saw it as “doing time”, I was forced to get my act together academically when I became severely chronically ill my freshman year at university. My work ethic changed completely because not being a full time student meant no insurance. Also, if I did not have a job in the future with good benefits, it literally meant death (I require a blood product to survive). So, engineering school it was. But now I don’t live in the USA so this is less of a problem. It is nice not to have to worry constantly about healthcare and having to work a job just for the benefits—-as in to actually be free.
More generally, i don't think we should make kids lives suck to prepare them for the fact that the rest of their life is also going to suck. That's not the way to make happy people who appropriately prioritize work/life balance.
Everyone is different though. Some people have lower stress jobs where they work for a single company and have plenty of time to learn new stuff on the job (or never really need to acquire new skills). But I work in consulting, so acquiring new skills while maximizing my billable hours is part of the game.
I'm also not the owner or anything of the sort; I'm a mid-level IC with no direct reports.
The second job is closer to homework, so long as you are doing it most nights and it takes some mental effort. And gee, it seems that having two jobs will pretty much kill creativity also and cause folks to burn out. At least with a second job, you are probably older. Teens and pre-teens simply aren't there mentally.
I will point out though that, if one is inclined to argue that school should prepare children for adult life, it sounds like this system is a pretty good mimic of the working life any given child is likely to have after they eventually leave school. Just replace homework with non-work obligations (or a second job).