Did you mean to write "Why /don't/ neurotypical people try to understand Asperger's?"
In response to your query, either way, I might add that many Aspies would argue that Asperger's is not a disability. It is a grey area - in many ways I feel "disabled" by Asperger's; on the other hand, we live in a neurotypical-dominated universe, so if it were flip flopped, one could argue that NT-ness is a disability! (Sorry I digress)
NTs don't try to understand sometimes, because they are clueless of what it is like to have an Asperger mind. People who are clueless about Asperger's sometimes don't consider it a "real" diagnosis - so it is a bit controversial. Even though we know Asperger's is a true, legit dx, some NTs don't see it that way.
Asperger's isn't as old a dx as some, so it has not gained stature completely as an established "disorder" in some people's minds. It is not like the straight dx of autism, which few people would dispute is a "real" dx. Asperger's IS a real dx, but some clueless idiots think that if a person is smart, they can't possibly be struggling socially. Some people don't think that social struggles alone are difficult or insurmountable. Some people think that it is mind over matter - if someone is of average or above average IQ, then they "must" be smart enough to overcome other things. It is not a matter of intelligence though.
People, like in your popular girls' example, can be cruel and will pounce on any "weakness" they perceive. They probably think it will push your buttons. They have succumbed to the mistaken notion that Asperger's isn't that serious. Who knows? However, if they did the same thing with race, they wouldn't get away with it as easily. It sounds like those girls are, in their true hearts, cowards.