I would not have guessed Tokyo would be in the top 10. To me it feels pretty tough for someone with a wheelchair to navigate Tokyo, with all of the stairs and escalators, but most of all the crowds. JR seems to do a fair job of providing assistance for people with wheelchairs, but my god what maze it must be trying to figure out how to make use of the various disabled amenities. Or, maybe its easier than I imagine?
Las Vegas I can understand. Singapore... well, maybe. Tokyo feels challenging on all levels.