Federal law is needed for something that crosses state boundaries. This kind of collusion between big players is likely to cross state boundaries.

Let's put it the other way: why do you think what works on a smaller scale (local companies) will necessarily tell us how it will work on a national scale (large national companies)?

This has long been recognized as a problem:

"People of the same trade seldom meet together, even for merriment and diversion, but the conversation ends in a conspiracy against the public, or in some contrivance to raise prices."

Adam Smith, The Wealth of Nations (1776), Book I, Chapter X, Part II

And therefore it's long been a part of US Federal anti-trust law and case law. Modern Republican administrations in particular have tended to focus their attention on these type of price fixing cases.

The local level is a good place to start; however, I believe the problem is more rampant. Google, Apple, and Pixar are mostly California companies. Google and Apple do have offices here in Texas where I work, and their policies were in affect here too. So the problem crosses state boundaries, which would need a Federal fix.