Even though disabled people are numerous, they aren’t so numerous as the able-bodied, and on average, they have less money than the rest of us. This is a vicious cycle.

Disabled people have less money, so manufacturers are less likely to make products for them, so the products they get cost more and are of lower quality. This leaves them with less money, which leaves manufacturers less apt to address their needs. And so on.

But sometimes a technology made primarily for the able-bodied has a side effect that helps the disabled. That’s called a positive market externality.

For instance, a disabled person doesn’t need to wait for a special-needs manufacturer to turn out a great audio player for listening to text-to-speech and audiobooks. She can just buy the same cheap, commodity players that we all buy.

Unless the greed of a small band of vocal dinosaurs gets in the way.

And that’s just what happened earlier this year, when Amazon shipped the latest version of its ebook reader, the Kindle, and included a feature that allows any text on the device to be converted to audio through some text-to-speech software. This aroused the ire of the Authors Guild, a moneyed, litigious pressure group that represents a paltry 8,500 American authors.

The Authors Guild claimed that the Kindle violates copyright (a ridiculous idea to anyone who understands copyright: even if converting an ebook to an audiobook infringes copyright, it’s not illegal to make a device that can infringe copyright, otherwise we’d have to get rid of every camera, phone, computer, photocopier, and iPod in the world), and demanded that Amazon pull the feature.

Amazon caved, saying that they’d allow authors to opt out of having the text-to-speech feature enabled, and around the country, disabled rights groups let loose a shout of dismay.

The Authors Guild argued that the Kindle is impossible to operate if you’re totally blind. Even if they’re right (they aren’t — many blind people routinely memorize sequences of physical motions that are performed on largely featureless surfaces, and many more have friends who can cue up an audiobook on their Kindles for them), the universe of disabled people who stand to benefit from the Kindle is much larger than just those who are totally blind.

All you need to do, blind people (says the Authors Guild), is abandon the value you get out of externalities from the market for the able-bodied, and limit yourself to the overpriced, underperforming devices developed as an afterthought in the market.

The Authors Guild will get their comeuppance, of course. So will we all. For though I write of disabled people as “them” and able-bodied people as “us,” it’s a near-certainty that I will end up with one or more profound disabilities if I live out my natural lifespan. It’s a rare person who goes into his seniority with all of his senses and faculties in perfect running order.

Because when it comes to assistive technology and externalities, there is no “us” and “them.” We’re all in the same boat, reliant on technology developed for toy robots to build our ingenious maker projects, reliant on text-to-speech for the day when our eyes dim or our hands stop obeying us.