Why a wheelchair symbol doesn't mean accessibility

I have seen this often enough, to make a comment on, what I am talking about is the practice of using a wheelchair symbol to give the impression that something is "accessible" or conforms to accessibility guidelines, see the examples below.

http://umbraco.com/products/more-add-ons/contour.aspx

figure 1

Google Captcha

figure 2

As someone who is colour blind, dyslexic and wears hearing aids I would class myself as disabled in some capacity in the fact that I have trouble with colour and sound but I would not say that the wheelchair symbol would summarise the fact that I have a disability.


Taking the image 'figure 1' to mean this conforms to WCAG, I lifted the overview from the W3C website (http://www.w3.org/WAI/intro/wcag.php):

"The Web Content Accessibility Guidelines (WCAG) documents explain how to make Web content more accessible to people with disabilities. Web "content" generally refers to the information in a Web page or Web application, including text, images, forms, sounds, and such."

I am pretty sure the W3C's explanation is not just solely talking about wheelchair users, so why is it used? It's because some people just don't think. Reading deeper into it, you will find its really about providing content in different formats or presenting the information in a format which is usable for other software (screen reading software etc).


Lets take the image in 'figure 2' and apply the meaning of the wheelchair, is the designer/developer who used this picture implying that only wheelchair users should click that button? Well, I don't think they mean that, because when you click that button the text shown is read out a loud so the user can hear it, I don't know about you but wouldn't a speaker icon or some graphic that says, listen to the text in the image, be more suitable?


Why is this imagery used so often, it can only be because that is what everyone else is doing. I hope by reading this you will inform others and think does this image convey the real meaning of what I am trying to say.


Edit:


When I tried to post this on facebook it gave me a captcha, which is a great example of how to do it:

Facebook Captcha