I have heard that when Google negotiates salaries, they often chime in about the value of the perks, and that employees should be willing to take a lower base bay because of the perks.
Google tells the IRS it is non-compensation, but tells prospective employees to value it as compensation.
This seems similar to touting "You get a Macbook Pro as your work laptop!" in recruiting materials (which I've seen countless times in recruiting pitches), even though that's undeniably a work expense when dealing with the IRS. This isn't a zero-sum game; just because a free meal at Facebook may be a net gain to Facebook (employees don't need to go off campus to work and thus can be more productive) doesn't mean the employee gets no benefit out of it and shouldn't consider it as a plus.
Google tells the IRS it is non-compensation, but tells prospective employees to value it as compensation.