I have spent twenty minutes trying to reword this so it doesn't sound snarky, but I can't seem to pull it off without changing what I want to say, sooo... Not being snarky, promise!!
Maybe it's just me, but I've always thought that most adults don't give kids near enough credit. Thinking that a toddler who is taught that instructions worded as commands are exactly that, commands, and instructions worded as questions are requests (ie, optional) will obviously grow into an adult who can't tell the difference between a friend's request and a boss's (or a cop's) politely worded instruction kinda seems up there with more mainstream folks who see a breast-feeding toddler and somehow extrapolate a breast-feeding twelve year old.
I'm still working on how it would all look in practice, exactly, but it seems to me that it should be possible to teach a child to be polite (and that parents always have the option of "no", while kids don't always have the option) while still telling when I mean "do it now" and asking when I mean "it's okay if you're busy".
The best teachers I ever had always established the rules, THEN eased up on the strict observance of formality. Taught the basics before things got complicated. Not the greatest analogy, but... identifying an instruction that was worded as a request seems like a secondary skill... so they might need to learn the primary skill of id'ing and following a plainly stated instruction first?