The issue is that most people are undereducated about those within the disability community. The thinking is, I think, probably that it would be easier to avoid looking than to gawk, and for people unused to contact with people shaped so differently from what they're used to, it can be hard to find a middle ground there.
You're right, there is a problem. But you probably shouldn't blame the people for it. They just don't know any better. Your boy and countless others like him who face similar challenges in their lives are always in need of passionate, outspoken advocates and people who will teach on their behalf.