Accessibility Is Market-Size Arithmetic, Not Charity

Most arguments for accessibility are moral arguments. Be kind. Do the right thing. Don’t exclude people. These arguments are correct, and they mostly don’t work. I know they mostly don’t work because the web is still full of sites that a blind person can’t use, built by people who would never describe themselves as unkind.

So let me make a different argument, one that has nothing to do with virtue. An inaccessible website is a store with a broken door. Not a locked door, which at least tells people they aren’t welcome. A broken one, which lets some people in and silently jams for others, and the owner never finds out because the people it jammed for don’t come back to complain. They just leave.

The arithmetic is simple. Some fraction of the people who want to buy what you sell can’t see well, or can’t see at all, or can’t use a mouse, or can’t hear, or can’t process a wall of low-contrast eight-point text. That fraction is not small, and it is not fixed. Everyone who lives long enough joins it. Eyesight fades, hands get shakier, patience for tiny tap targets runs out. If your customers skew older, or will someday, you are building for your future users’ bodies whether you plan to or not.

And the fraction is bigger than the disability statistics suggest, because most accessibility failures also hit people with no disability at all. The person reading your site on a phone in bright sunlight has the same problem as the person with low vision: your gray-on-white text is invisible. The person holding a baby in one arm navigates like the person who can’t use a mouse: one hand, keyboard, whatever works. The person watching your product video on a train without headphones needs captions exactly as much as a deaf person does. Accessibility people call these situational disabilities, which is a useful phrase because it makes the point that disability isn’t a separate population. It’s a state everyone passes through, sometimes for a minute, sometimes for the rest of their life.

Here’s what makes this strange as a business problem: the loss is invisible by default. If your checkout throws an error, you see abandoned carts in your analytics and you fix it. If your checkout can’t be operated by keyboard, you see nothing. The blind user who hit your unlabeled button didn’t file a ticket. Their screen reader announced “button, button, button,” they gave up, and your analytics recorded them as one more anonymous bounce, indistinguishable from someone who just wasn’t interested. You are losing sales and the loss is filed under “conversion rate,” a number everyone assumes is about copywriting.

This is why I think of accessibility as market-size arithmetic. Every accessibility failure shrinks your addressable market by some percentage, and you never get a report about it. When people do the math at all, they do it backwards: they estimate the cost of fixing things, which is visible, and weigh it against a benefit they can’t see. Visible cost versus invisible benefit loses every time. That’s the whole reason the web is like this. Not malice. Accounting.

The fix costs less than people fear, because most of it is embarrassingly basic. Images need text descriptions so screen readers can say what’s in them. Form fields need labels attached in the markup, not just floating nearby. Buttons need to say what they do. Text needs enough contrast against its background to be readable. Pages need to work when you press Tab instead of using a mouse. None of this is exotic. It’s mostly HTML used the way it was designed to be used, and the WCAG guidelines that formalize it are less a legal document than a checklist of ways doors get jammed.

There is a compounding return, too, and it’s not a coincidence. A search engine crawler is, functionally, a blind user. It can’t see your images either; it reads your alt text and your heading structure. A site that a screen reader can parse is a site a crawler can parse. Pages that work by keyboard tend to have sane, well-structured markup, and sane markup is faster and easier to maintain. I keep noticing this when I look at scan results in GazeSite, which I built to audit sites across several areas at once: the accessibility findings and the SEO findings point at the same underlying sloppiness so often that fixing one column quietly improves the other. Accessibility isn’t a tax on your site. It’s a proxy for whether your site is built well.

I’m not saying the moral argument is wrong. It’s right, and for some people it’s enough. But you shouldn’t need it. If a consultant told you that a segment of ready-to-buy customers was bouncing off your site for a fixable reason, you wouldn’t ask whether serving them was charitable. You’d ask how fast you could fix it. That’s the correct frame. The kindness is real, but it’s a side effect. The main effect is that your door opens for everyone who was already trying to walk through it.