Why is it a handicap? I've seen poor Asians who go to the same types of schools tend to do just fine.
That said, in the US, many people (Asians included) can go to shitty schools and still succeed. Their success is despite the formal education they got at a low SES school, not because of it.
Generally when you see elite school success from students from low-SES areas, it is due to substantial intervention at home and/or extracurricular education/tutoring.
You ask why it is a handicap. If they could get quality education during school hours, their extracurricular hours could be used for deeper study or more interesting endeavors (e.g., research projects).
What do you think explains the difference?
> which I've heard is actually very easy once you get in
Very dependent on what classes you take.
The Asians, at least the ones who come to the US, being a far more elite group in terms of genes for academic success.
I call it as I see it, and I'm generally not wrong.