This whole argument makes me think of efforts in education to develop teaching methods that maximize student autonomy, even though I think this may be a slightly simpler issue seeing as most people aren't having 20 kids to work with lol. Two points come to mind for me:
1. "Childhood" is a socially-constructed term, which is inevitably problematic. "Childhood" used to end as soon as one was physically mature enough to reproduce; today it's a matter of when you're "done with school" or "don't need parents to pay for you". Then, you've got the issue of childhood being drawn out based on a person's demographic membership: at some points (arguably even today), Black people were considered "children" even if they were physically mature enough to reproduce just because they "needed to be taken care of" by white people; similarly, mentally handicapped people throughout time and even today, although not explicit called children, are treated as children. Also loosely connected: people with severe psychological issues are to a degree viewed as "children" in need of authority.
2. I think a distinction has to be drawn between guidance and authority. I've been forced to learn the subtle difference in my work with mentally handicapped people and in my work in education research. One key difference is that authority ignores autonomy while guidance scaffolds autonomy. That sounds vague, but what I mean is that guidance only ever does things that even slightly seem authoritative when it's going to produce further autonomy for those being guided. Another aspect is that guidance means helping a person (young or old, mentally handicapped or not) make informed decisions, regardless of whether you personally like the outcomes. Prime example: Where I used to work, I had people who would refuse to eat a meal. Even though I'm thinking "NOOOO, SHE NEEDS TO EAT

!!!" and "BUT EVERYONE EATS DINNER AT 5PM HERE! THAT MAKES MORE WORK FOR ME!", I had to respect her right to decide to not eat until she felt like eating. Keep in mind this was a person who couldn't even carry out conversation with me and didn't understand explanations of things that would occur in the distant future. In the worst cases, a person may have refused to eat and began losing weight to the point where his/her health was jeopardized; seeing as sickness would impede his/her future autonomy, we gave the person nutrition shakes to bring the person up to speed health-wise.
I think a lot of the child autonomy issues we face are a direct result of our expectations in capitalist societies...kids NEED to do A, B, and C because they won't go to college if they don't, and if they don't go to college they won't be able to buy a house, and if they don't buy a house...and you see where I'm going with it. In relation to what I've seen in my research work, it's important to recognize that a person's refusal to do something shouldn't be viewed purely as a refusal to "take good advice". People's negative attitudes and feelings need to be respected because it often can tell us something about what the person is experiencing and whether it's REALLY such "good advice" that's being given in the first place. For example, if a kid refuses to eat, maybe it's because his/her tooth hurts and you just didn't realize the kid needed dental treatment. I think it's possible to provide guidance that supports autonomy...it's just that it likely will get you called "crazy" by everyone else, people will be pissed that your kid is the one yelling in public, and you may even face legal and social sanctions for not forcing your child to submit to authority.