University admins send us automated third party a11y reports constantly, demanding that we make all of the recommended fixes immediately. We learned really quickly that several of these reports are very opinionated about how to implement ARIA tags, sometimes in ways that contradict the documentation. It can be hard to explain this to a customer trying to protect themselves legally.
In addition, screenreader apps are implemented inconsistently, and reproducing/debugging the screenreader bug in your app can be really infuriating. I felt truly horrible for people who use them on a daily basis because it's an utterly prehistoric experience compared to using the web normally.
The last thing is that we've had issues with getting a11y right with our front end frameworks at times to address these screenreader bugs.
Ultimately, a11y is so painful and costly for us to get right that it takes up a major chunk of our development efforts these days, and we all hate working on them.
The state of developing and maintaining accessible web applications feels like a sad joke given the industry's mantra to make the world a better, more connected place.