For such jobs, big corps do hire PhDs. These jobs are almost always in a research department (i.e. they won't hire a PhD to code). But these jobs are maybe 1% of all jobs in big corps.
Nowhere near 1% in my experience. Also, even in research arms, many masters level students are accepted (though it really depends on how low level the research activity is at that particular company, so this is going to vary wildly among different companies)
