Unkillable Access / What automated accessibility testing misses

What automated accessibility testing misses

Automated tools prove a subset of WCAG. Here is exactly what this scanner checks, what it cannot, and why nobody honest sells you a compliance score.

This page exists because the alternative — implying a scanner covers everything — is the exact claim that drew a $1,000,000 FTC penalty in this industry. So here is the honest boundary.

What a machine can prove

These are checks where the markup either passes or it doesn't, with no judgement required:

• An image has no alt attribute at all
• A form field has no associated label, and a placeholder is not one
• A button or link has no accessible name
• Declared text and background colours fall below the required contrast ratio
• Heading levels skip, or the page has no h1
• The page declares no language
• An aria-labelledby points at an id that does not exist
• A positive tabindex scrambles keyboard order
• The viewport meta tag blocks pinch-zoom
• Two elements share an id

What it cannot

These require a person, and no tool should claim otherwise:

• Whether alt text is accurate. A scanner sees that alt exists. Only a human can see that a photo of a fire exit is described as "team photo".
• Whether the reading order makes sense. Markup can be technically valid and still narrate as nonsense.
• Whether a task can be completed. Every control on a checkout can pass every automated check while the checkout remains impossible to finish with a screen reader.
• Whether link text makes sense in context. "Read more" is detectable; a link labelled plausibly but pointing somewhere unexpected is not.
• Whether error messages are usable. Being announced is not the same as being comprehensible.
• Whether video captions are correct. A caption track can exist and be wrong or auto-generated garbage.
• Contrast the tool cannot see. Where colours come from images, gradients, or scripts, we report the check as undetermined rather than guessing — an undetermined check is not a pass.

So what is an automated scan worth?

A great deal, as a first pass. Automated checks catch the high-volume, high-impact defects that are cheap to fix and genuinely block people — and they catch them across every page, consistently, for free. That is real value. It is simply not the whole job, and the responsible thing is to say so.

For anything user-facing and important, follow an automated pass with testing by someone who uses a screen reader daily. Ideally, pay them.

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