”Each screen reader does things a bit differently, so testing real behavior is important.”

Correction: each screen reader + os + browser combo does things a bit differently, especially on multilanguage React sites. It is a full time job to test web sites on screen readers.

If only there was a tool that would comprehensively test all combos on all navigation styles (mouse, touch, tabbing, screen reader controls, sip and puff joysticks, chin joysticks, eye trackers, Braille terminals, etc)… but there isn’t one.