The carrot is clearly not enough for accessibility. That's why the ADA provides the stick.

There's a large benefit for society when society is more accommodating. It's easier to notice the accommodations for limited mobility; but if you have a new limit to your mobility, you'll notice everywhere they aren't. Accommodations for limited vision are often less noticable if you don't have experience with limited vision, but many of them are not very expensive if done at the right time in the project.

I understand your point, especially for company websites whose products/services aren't oriented to the blind.

However, there are many companies with products/services that are just as much for the blind as the sighted (government, insurance, legal, medical, etc.) and many of them don't even make an attempt. The blind are still people and they should have equal access.