Disabled people are as different from each other as we are from nondisabled people. Sometimes people don’t understand this. Instead of looking at specific impairment, they look at what they think of as severity. It’s as though they’re thinking, ok, on a scale of 0-10, how disabled is this person?
This can lead to a bizarre opposite reaction to disability and disabled people. People not only respond to disability based on stereotypes, they often respond based on the stereotype of a completely different disability.
For instance, sometimes people who think of blindness and deafness as the same level of disability will respond to blind and deaf people interchangeably. (And often in ways that wouldn’t be helpful in any case). Because they don’t think about vision or hearing, they think about a severity category.
Eg: a waiter who thinks this way might see two people signing to each other, notice that they are deaf and bring them a braille menu. Or they might, halfway through taking an order, notice that the customer is blind — then start talking really loudly.
They don’t pay attention to the physical reality of the person they’re interacting with. Instead of thinking about what this person’s disability is and what accommodations they need, they’re looking in a box marked something like “what to do when you meet a level-8 disabled person”.
In real life, disability isn’t quantitative, it’s qualitative. Having a disability means something physical and/or cognitive, which will be different for every disabled person. It matters what type of disability someone has. It matters how that disability affects them, specifically. It matters what their preferences are, and what they’ve found works for them. Thinking in terms of severity level won’t tell you any of the things that matter most.