Every so often, a popular answer to a question on this site receives a comment like "looks great, but how accessible is it?", or "try that out with a screen reader and see how much fun you have". These comments make me realize that I don't think about accessibility very much, if at all.
What is the appropriate response to questions of accessibility? It seems that sites and applications either worry about accessibility or not, and my assumption is that the sites that worry are a lot fewer in number. I often read things like "We are working on an accessible site for a client", but how did that client decide that accessibility was something they were going to spend money on in the first place?
Is it a legal compliance thing? Is it industry driven? It it purely related to your audience? My impression from reading about the topic is that accessibility is a often concern for federal or government sites, but why these sites in particular? Are they more likely than any other sites to receive traffic from the types of visitors who would benefit from accessible design?
Of course the answer to this overall question should be something like "All site owners should be concerned about accessibility all the time", but that's not how things are in reality and it's unlikely to become that way overnight.
How can a site owner or developer know when they really need to consider making their sites accessible?