Visibility and mobility can be tricky things. A disabled friend from Bulgaria who visited me a couple of years ago was absolutely amazed by the many things available in this country to improve mobility of the disabled (ramps, lifts, public restrooms, transportation, etc.) - none of which could be found in Bulgaria. OTOH, public transportation, and public sphere in general, are very much limited in this country - people tend to live and move around alone in "bubbles" aka cars. So it is not necessarily the obstacles to mobility (in this respect the US is probably better than most countries) but the compartmentalization and privatization of the public sphere that makes the disabled "invisible."
wojtek