It might be wishful thinking, but part of me wonders if Steve Jobs might have actually been able to push back a little and prevented Apple from joining the program at the same time as Microsoft/Google et al. Apple isn't known for being outspoken about privacy, but Jobs is a formidable character to deal with and, well, if anyone had the balls to say 'no', he did.
Apple wasn't added until after Jobs died, years after other major players: