I think this reaction occurs for a few reasons – people simply don’t want to believe that a society similar to theirs can possibly do not only such things but worse than what occurs in the novels. Another reason is that anything aimed at younger readers is automatically dismissed.
And yet another of course is that YA fiction features in their view too many female heroines and characters in general, as most people perceive a discussion to be female-dominated if it has above 30% female participation.
One of the fucking reasons I read YA so much is that women aren’t treated as sub-humans in the genre – and the writing is often a lot better and tighter.
It’s funny also that The Hunger Games premise is seen as ridiculous yet having 12,000+ people die of firearm homicides a year in this country is seen as normal, and having 50,000+ people perish because their medical care is inadequate – well, that’s just how things go.
People tend to ignore the horrors all around them, it seems, while concentrating on milder fictional ones.