It's not the whole story but part of what makes accessibility hard is toolkits not being designed with it in mind from the beginning. That's how you end up with

It's not the whole story but part of what makes accessibility hard is toolkits not being designed with it in mind from the beginning. That's how you end up with things like accessibility "modes" that are really just skin deep themes instead of proper modes. Good accessibility capabilities requires flexibility to be at the core of the UI toolkit. You basically can't make assumptions anywhere.