The Disability Discrimination Act 1995 make it illegal for web sites to discriminate against a disabled person.
Traditional web design techniques create web sites that do actively discriminate against disabled persons by making it harder for them to use the web site than it needs to be. Typically graphic design techniques put more emphasis on making a web site look the way it is designed to look rather than allowing for the different requirements of the end user. So in most cases Accessibility features are disregarded or ignored completely as they are an inconvenience that may be restricting the web site designer. The web site owner is often” none the wiser”.
Web sites must make “reasonable adjustments” to the way in which they work to enable the disabled to use them. If you own a commercial website which is inaccessible to the disabled, you could be be sued as a result, and damages could be awarded against you.