So, is it basically a liability issue from Disney's point of view?

CNN.com - Disney turns away visitors on Segways

Disney says visitors aren't allowed to use them because they're not FDA approved as medical devices. But people with neurological or other mobility issues say it means the world to be able to enjoy activities standing up, eye to eye with others, rather sitting and looking people in the waist.

I guess Disney's concerned that they could somehow incur liability in terms of the devices operating in the parks. Still, from what I understand most anybody would benefit from a Segway when visiting Disneyworld or other Disney venues; they're huge.

I can definitely understand the anger of those denied access, though, and their desire to take their business elsewhere. My feeling is they'll eventually lighten up, especially if the device is recognised as a benefit for people with disabilities or at least is sold in enough numbers to establish a good safety record.

I'm not sure the liability would be any different than, say, if someone tripped on a kerb or because they were using a stroller--which as far as I know, isn't a medical device.