They are man-sized and almost or equally as intelligent as an average human...yet still a "kid".
Right, that's why I specified "as long as it acts/talks like a kid". Or a teenager. If a hatchling acts like we would expect an adult, then yeah, less people will have a problem with killing it, but that's to be expected. If someone can't recognize a kid as a kid, they won't treat it like they would a kid.
You may be conflating maturity with intelligence; just as it is possible to find a manifestly stupid adult who possesses enough survival skills to scrape on by, you can find a brilliant kid that nevertheless has many lessons on practicality ahead of them. I dislike anthropomorphizing monsters any more than is absolutely necessary, but I imagine a Hatchling Chromatic Dragon (sans the White variety) would behave like a genuinely smart human child with a firmly exaggerated sadistic/brutish streak.
Originally Posted by Niara
Sunless Citadel, a very famed 1-4 adventure module brought forward into 5e in Tales from the Yawning Portal, has an ice dragon wrymling in it, towards the end. It's not actually the final encounter, and the adventurers are gently pushed towards subduing it rather than killing it, for in-story reasons.
For the record, yes, Whites are brutish and dumb, as far as dragons go. Comparatively, Greens are the schemers and enjoy plans and plots more than any other chromatic type.
That reminds me...
^ At first blush, the depicted scene is slightly amusing; once you learn the deadly nature of even the youngest dragons, you recognize the difficulty of such an achievement.