I've had a hearing loss my whole life and the number of people who have claimed it wasn't real always befuddled me. I never understood why they thought that. It never occurred to me it that it might be because they can't see it. I figured it was just my bad luck I ran into so many people like that so I'm surprised to see this phenomenon described in this manga.
Yeah I think people have a hard time accepting things that are out of their personal "norm", especially if they can't see them. You get this with things outside of disability as well, homosexuality is a big one. There's a lot of "you're not REALLY interested in people of the same sex" that goes around, along with other phrases like people saying homosexuality is "just a phase".
Oh and depression is commonly dismissed, and still unfortunately not taken seriously a lot of the time. Heck though I think some people are even dismissive of things they can see, like telling someone in a wheelchair to get up and stop faking it. Dismissive behavior like this is very frustrating and unfortunate.
