Isn't it odd how we as a society consider it wrong to make fun of someone with a physical disability, but ok to make fun of someone with a mental disability?

Don't misunderstand--I'm not suggesting we should make fun of either, but think about it:

Doesn't it seem people would make fun of people who may not be able to defend themselves or get away, rather than people who might be crazy and cut you? I know most people with mental illnesses aren't crazy, but I'm making a point of how dumb some people who are rude enough to ridicule disabled people are.