Because Unity provides no native support for outputting text or controls to the screen reader, on any platform. By default, when a Unity game is opened, the screen reader can only detect a blank window. You as the game developer need to write a bunch of special code to provide functions that most screen readers would provide automatically, if you were using another engine. Apparently the
$1 will soon solve these problems, at least for IOS and Android. Unfortunately, as far as I can tell (I'm not a game developer so am outside the community looking in, as it were) this plugin hasn't officially been released. It has been successfully used in one commercial IOS/Android game called Crafting Kingdoms, and I think that game might have been written by the studio that employs the woman who works on the accessibility plugin. Anyway, that's a really fun game, and the accessibility works well. So the best advice I can give you is to contact her, and see if/when you can use this plugin in your own work.