Also not OP, but... Getting things to be accessible (in practice: not just what some tool spits out in a report, but making the app/site useful to a real user

Also not OP, but... Getting things to be accessible (in practice: not just what some tool spits out in a report, but making the app/site useful to a real user with disabilities using a real browser of some sort) is not that bad as long as everyone's on board (if the designer wants everything drag & drop in red and green tones, you're kind of screwed). Catering to screen readers is hard for the same reason supporting any non-60%+ user base browser is (uncommon mobile browsers, IE, whatever). All browsers have bugs and quirks, and having less eyes on things makes finding bugs hard. Debugging in a browser you don't use as frequently is always going to be significantly more challenging. When its not a "standard" one, it can be hell. As another poster mentioned, a lot of the automated tools spit out a lot of false positives, and that adds to the burden.