[microtherion]

Ironically, I think the accessibility focus started because they were a fraction of today’s size: in the early 2000s, section 508 requirements were becoming more stringent; there was an increasing risk that Apple would get shut out of government contracts, and due to the small market share of OS X, it was not considered a viable market for commercial screen reader vendors, so Apple decided to roll their own.

Thanks to strong leadership in the accessibility team, there was an increasing buy-in from the top, and throughout the company. Today, accessibility is indeed in Apple’s DNA, but initially, there was quite a bit of genetic engineering and (dare I say it?) government regulation involved.

[bluGill]

Apple was known for easy to use in the 1980s. While that isn't entirely accessibility, the two are related. The early macs had some accessibility features.