It's a completely different negotiating situation. 1) The company knows exactly how much you're currently being paid. 2) The company doesn't have to tempt you

It's a completely different negotiating situation. 1) The company knows exactly how much you're currently being paid. 2) The company doesn't have to tempt you over an activation energy hump to change what you're doing. 3) Unless things have changed radically over the past year, you're probably doing pretty much the same job as when you started, so you've not got much leverage, and the company knows you'll likely just carry on doing it. 4) The company knows that if you do want to change jobs, that's effort you need to put in over and above your current exertions, and most people won't bother.