According to advocacy group Alliance for Inclusion in the Arts, 2200 actors are self-identified as persons with disabilities with Actors Access, a well-known national casting service. Without many opportunities, these performers often find it hard to build the resumes that will get them steady work. "Playing disability is a considered a technical skill for an actor, and casting directors and producers prefer to seek non-disabled actors with long track records," says Howard Sherman, director of the Alliance. But as disabled performers become more vocal, there is hope they'll become more visible too.

As a playwright who underwent a below-the-knee amputation at age 38 during treatment for Ewing's sarcoma, I have lived as both an able-bodied and disabled person and artist. I understand that casting entails more than a search for diversity. But I’ve also come to believe that leaving out actual disabled people undercuts the power of works ostensibly about disability.

The late, disabled playwright John Belluso had a theory about why actors who play disabled characters often win Oscars: It is reassuring for the audience to see an actor like Daniel Day Lewis, after so convincingly portraying disability in My Left Foot, get up from his seat in the auditorium and walk to the stage to accept his award. There is a collective "Phew" as people see it was all an illusion. Society’s fear and loathing around disability, it seems, can be magically transcended.

This same logic can be applied to any representation of disability by an able-bodied actor. A lot of teenagers going to see The Fault In Our Stars already knows Ansel Elgort has two full legs. Broadway audiences know from having seen them previously that Sutton Foster bears no facial scarring and Daniel Radcliffe has no physical limitations. It is obvious the conjoined sisters in Side Show are two fully separate women, and even the convincing CGI amputation in Orange Is the New Black strikes our eye in a slightly false way.

This is not incidental but central to the success of these representations. They provide us with the comforting assurance that we are not witnessing the actual pain and struggle of real disabled human beings; it is all make believe.

Able-bodied actors can listen to the disabled, can do research, can use imagination and empathy to create believable characters. But they can't draw on their direct experience. That means that audiences will be able to "enjoy" them without really confronting disability's deepest implications for human life.

Often, one fears, that’s the point: Pop culture’s more interested in disability as a metaphor than in disability as something that happens to real people. For example, in his review of Side Show, New York Times theater critic Charles Isherwood wrote, "Of course, in some sense, we all know what it’s like to feel self-divided, or alienated from the world, which is what makes 'Side Show' emotionally stirring." Disabled characters are often seen as symbolizing the triumph of the human spirit, or the freakishness we all feel inside. That may be another reason disabled actors are overlooked—they don't allow disability-as-metaphor to flourish as easily.