Ramps, escalators, tiles, and seating. There is nothing inherently not accessible about subways, we just choose not to make them accessible. When I was in Japan, there didn’t seem to be any issue preventing wheelchair users, old people, or blind people from using the train system. Escalators can be used by people in wheel chairs and old people (and presumably blind people too, but I’m not sure.) There were tactile tiles in the floor to guide the blind, and there was plenty of seating specifically dedicated to old people, disabled people, and pregnant people. There were also wheelchair accessible cars on every train. As far as I could tell, it seemed just as accessible and easy to use for them as anyone else. (Also elevators were only usually kept open for the people who needed them)