And what existing disparities are we talking about here? The fact that new hires are getting 40% more than what a 10 year staff is currently earning? Or that someone with less experience are getting a higher grade code than you (and the 40% pay disparity)?
Just keep in mind, this is their country and company and they can do what they want. If you do not like what is on offer, just say no thank you. If you are already here and aren't happy, do find another job back home or elsewhere and be happy.
I would respectfully submit that we expats are already paid a hefty premium over the local population, presumably to bring in our expertise and advice when appropriate. Some expats speak up based on a simple respect for their hosts recognizing that this is specifically what they are paid to do. Others sit quietly and take cash even though they know something is being run into the ground. For the sake of the company and host country I more wish the latter would find a job back home.