i can't speak for all rail lines through tokyo - the ones i've taken have been fine. quick searching suggests they're probably mostly fine. the standard for me is not "is it easy?" but "is it possible?" or maybe "is it not a huge pain in the ass?" - it's always cleared that for me. signage could often be better, i'll definitely say that.

tokyo more broadly: it's improving, but yeah, it's nowhere close to 100%. obviously i won't disagree with you there.

and i didn't mean to come off as too harsh. but i imagined someone reading your comment and being deeply discouraged (as i might have been, many years younger) when in reality tokyo has possibly one of the best and most accessible subway systems in the world.

it's not all roses, but outside of the US, most of the world is not so wheelchair-friendly (in my experience and talking to disabled folks, at least). (and don't get me started on NYC, which is just wheelchair-hostile.)