Is that really an apples to apples comparison? Apple, Microsoft, Google and Samsung all have a bit of crossover here and there, but for the most part those are four different companies with four different missions. Google and Samsung are in so many different areas that it would stand to reason that their R&D budgets would be so bloated. I don't keep up with Microsoft too much really, so I have no idea what their budgets in that area are.
Then there's Apple. As of right now they are really in 6 different areas: desktop computers, mobile computers, tablets, phones, the cloud, and software. They've obviously started recently tinkering more and more with TV and wearables seem like the next frontier for them. But just looking at a broad comparison of the portfolio of products that each company you mentioned offers it would be a pretty obvious assumption that, based on each company's goals, that Apple would bring up the rear in R&D spending among them.