I work at a web shop, and we're convinced that Apple is deliberately failing to make improvements to Safari (specifically on iOS). The theory is that they are conspiring to lock in people who depend on the platform, but also prevent them from delivering anything approaching the quality of native apps on iOS.
Though usually I try to avoid thinking of conspiracy; the more I work with their platform, the more reasonable this theory sounds.
I have been solicited to work on WebKit for Apple, but given how isolated Apple employees seem from the world, I don't think I could do it. I'm not willing to sign away my personality or existence for cash-on-hand. I suspect they're having trouble hiring people to work on WebKit, because although I think I'm a pretty good developer, I'm not the top of the barrel when it comes to WebKit developer candidates.