I'm not overseas, yet, but I do agree that Jinchafa has some valid points.

My father came abroad and worked for a local (accounting) firm when he and my mother were first married. At that time, "contract" employees had many perks included with their salaries - including housing - and they were better paid than the "locals", anyway. When enough local employees protested, things began to change, in almost all professions.

Today, local workers get a much better, more equitable wage to live on, and "contract" folk get the same salary, with help. (eg. Housing is found for them, but is no longer an inclusive perk. In fact, they often prefer to move to a cheaper place, once they've been here awhile).

So. I would say that you (we) can ask for higher pay, since it may very well benefit your (our) host nation's teachers as well. Especially since I understand that most Locals are not so well compensated as the overseas staff.