Alex, I’ve heard the point made that people with disabilities are far more likely than others to engage in commerce online rather than in brick-and-mortar stores. It makes sense — at least for people with mobility or visual impairments, the very disability that makes using the Web a challenge makes getting to a store even more of a challenge.
The significance of that is that the relatively small (as in “much less than half the general population”) number of people with disabilities are a somewhat larger chunk of the group that engages in online commerce, in the first place, and somewhat more likely to buy from an online merchant, in the second place. But they’re also highly likely to ditch a site that isn’t accessible in favor of one that is.
So whether they’re ignorant, biased, lazy, or greedy, by ignoring a few percent of their potential customers these online merchants are losing a goodly chunk of their potential sales.
In time, the situation might become self-correcting. One can only hope so.