Accessibility audits done by automated software are an important part of the journey to compliance with WCAG 2.0. However, accessibility testing software is not infallible. These tests don't possess the subtleties needed to identify areas of only partial compliance with regulations.
Even when the automated system says PASS, there could still be significant accessibility obstacles to overcome. These are the top five issues that frequently fool automated software:
Usually, automated programs are just looking to make sure your images have something in the ALT text field. Those descriptions fail when the text does not describe the picture, is unrelated to the purpose of the image, or is stuffed with keywords.
Links are essential for helping website visitors understand what you do, but too often those links lead to resources that are inaccessible for many visitors, such as PDFs or uncaptioned videos. Everything might be up to par on your page, but your website will still fail the WCAG 2.0 audit if visitors can't follow your essential links.
Automated systems can tell you what's wrong, but they often fail to tell you what you should be doing to correct the problem. That's often true when elements are labeled incorrectly or without the proper detail. Assistive technology tries to understand the purpose of each element and auto-assigns a label, but when it can't understand elements or mislabels them, the user will be completely lost on your page.
Website owners often spend a great deal of time making sure that a user can navigate the website with a keyboard only, but then inadvertently ignore the focus. Users with screen magnification or those using only keyboards won't have any idea where the input field is unless it is specified. A related problem is keyboard traps, wherein tabs just toggle a user back and forth between two fields. Automated tests normally can't test for where tabs take the visitor.
You are probably careful not to convey information with color only, but were you aware that certain color combinations can be a problem too? Most automated tests don't have the fine-grain intelligence to detect color combinations that fall outside acceptable ratios for contrast.
Although we just discussed how frequently automated software can fail to identify accessibility issues, the opposite is also true. Automated tests tend to find too many false positives, erroneously indicating something is wrong when your website doesn't need any more work. The solution is a mix of testing methodologies by professional testers. Talk to accessibility experts who have the experience working with ADA and WCAG 2.0 guidelines and are trained to put themselves in the place of website visitors with disabilities and discover where your website could fail compliance testing. That's the true face of due diligence.