That's true, but HR people don't generally have the authority to negotiate outside of narrow parameters. They're recruiting for particular jobs, with particular salary ranges.
You're probably right. Just so you know though, one of the Big Lessons I've had selling to big companies is to figure out:
(1) The times you are asking your counterpart to spend "her own money" (from her budget, outside her range, etc)
(2) The times you're asking your counterpart to spend play money.
It's always helpful to remember when you're hesitant to ask someone at a big company to pay you for your product or service that they aren't paying you out of their own pocket.
