OK i have done research on this topic and it actually is very interesting.
While the physical aspect of riding a Segway (standing up and swaying while turning) for a prolonged period of time can get tiring and thus many disabled and some non-disabled user have made a seat or small stool for the platform base. Also most disabled users have a small handicap sticker or placard on the lower control shaft or on a handlebar bag (12.0 bag). While some also carry a doctors note and/or legal papers of that states laws on the use of a Segway/empad device. But now some people are probably thinking why don't some users just get a power wheelchair, some go faster and all are welcomed in all public places. This situation though mainly is a mental preference that first came about with the ibot. These devices alike can place the user at a normal standing height of an adult. This difference compared to the sitting height of a normal wheelchair places the user face to face with others where in a wheelchair they are always looking up to talk to others. Also with a Segway, the user does not have to specifically look disabled as where in a wheelchair the user normally is and does appear disabled.
[edit] OK also i forgot one thought. A major reason as to why the Segway isn't promoted as an assisted health device like the ibot, is because if legislation was passed for this device to be like a wheelchair, and the FDA accepted it, the Segway HT would not be available to everyone but only to those with a doctors release for use. [/edit]
I hope this answers some questions and if theres still some others, take a look at the
DRAFT (DISABILITY RIGHTS ADVOCATES FOR TECHNOLOGY) website.
~Michael