Apparently, the people in Westeros are too busy sword-fighting and getting naked to invent the goddamn wheelchair.
But why is his name Hodor? Did he have annoying, Gwyneth Paltrow-esque celebrity parents? The answer is far more complicated. Basically, Bran's time-travelling melted poor Hodor's brain -- as his future self is being commanded to "hold the door" to block a horde of White Walkers, his past self starts muttering "Hold the door" over and over, eventually morphing into "Hodor" (a transition that caused headaches for the show's international translators). So, people just started calling him that.
If the same rule applied to 12-year-old boys in this universe, there'd probably be a hell of a lot more kids named "Boobs Pokemon."
That's a pretty intricate twist, but a few people actually predicted this outcome. How the hell? By doing what we do for a living: making dumb-ass pop culture jokes. Way back in 2008, before the TV show even started, a fan of the books posted this on a message board: