Most people are not recognizing the possibilities of an accessible website. They do however see the benefits of usability. This is a start, because accessibility IS usability. Usability IS NOT accessibility. 

When developing a website, the customer would demand it to be usable but will give no instructions whether or not it to be accessible. The customer cannot see the benefits of accessibility, because if you sell bicycles you probably haven’t got any blind or handicapped customers. A blind man is not blind to the issue of accessibility on the web or anywhere else I presume. The project manager is locked down by deadlines and probably will give accessibility a very low priority.

As I wrote before, it is not that hard to make websites accessible, but maybe you have to sell accessibility as usability, because usability is understandable by almost anyone. This might give you the little extra time it takes to make the website accessible and raise the overall quality of the website.

Accessibility is an abstract concept for the average web designer/developer, because he or she has never needed accessible web pages. A lot of people say that we all benefit from pages made accessible (here's one). One good example of this is keyboard shortcuts (accesskeys) and tab indexes. In my opinion it is also the only visible benefit of accessibility for people without the need, but that’s mostly because it’s good usability.

I have always been promoting web standards and good accessibility, and I’ve found two things to be true when I build for the latter. It is almost always damn hard to create a whole website validating for WAI triple A certificate, which is the highest degree of accessibility a webpage can uphold. On the other hand, I’ve found that if you can live with only one A or maybe two, it can be done somewhat easy.

One issue of making accessible pages is that it can take a lot of extra time. That’s why it is very important to implement accessibility from the beginning of a web project and not just at the very end. Always keep in mind the various ways doing things accessible and it will come a lot easier to you. You would have to know these techniques before you begin of course.

The easy thing for a developer would be to simply ignore the standards in order to meet the deadlines. In my opinion, that’s bullshit because it’s lowering the quality of the overall product. No customers are ever gonna ask you to make the site accessible, because they don’t know it is an issue. But as soon as someone complaints about it, the customer turns to you with as if it is your problem, and so they should. It is the developers fault. It all comes down to quality and taking pride in what you create as a developer. If the website isn’t accessible, the quality isn't up to standards and you have to fix it as a bug.

I’m not saying that every website should validate to a triple A, but that the basic do’s and don’ts of accessibility should be taking care of.

I would suggest always validating for accessibility and making sure the biggest issues are taking care of as a minimum. It is not that difficult and it is a fairly quick fix to a potential demand from the customer in the future. Be careful not to take this topic lightly. If you do not learn the basics of accessibility, it can give you trouble in the long run.