This sounds great in theory. I've had a ranges that was very healthy on application, gone through a lengthy process including showing work examples and meeting the team to be offered below the bottom of the original offer - "We feel like this is a good starting sallary, we will review it in 6 months" - "The company has changed its investment direction so this is a revised number" - "We've created a new role that better fits your needs" etc etc...

This law will force them to actaully stick to a number.