Google has that experience because of their own research. There's nothing to say that any other company of large enough size can't do research of their own. This is especially important to consider when you think about the level of secrecy Apple has when starting an internal project. Despite all of that, it's super unlikely Apple would make a car. It's just too weird.
Google bought Thrun's self driving car startup, well after he led the team which won the DARPA Grand Challenge with Stanley; and subsequently acquired additional startups with autonomous vehicle technology. Apple purchased chip design firms to bootstrap its integrated chip capabilities, quite successfully. They've demonstrated the ability to assimilate outside technology.
