"spending depends on your nationality"? huh? spending depends on the lifestyle that you are living.. or also may depend on your capacity to spend.. but, there i agree with the thing you mentioned about the salary range.. because there is really a salary bracket in all industry.. because here in the middle east if you're a westerner/ european, you'll get much more than people coming from asian subcontinents. or far east, south asians.. why? there are some valid reasons... one thing is your country's cost of living, if you are westerner/euro engineer, you wont accept a salary of 3000 dollars, because that's not the market of engineers in your country.. but for asians, 3000dollars salary here is quite good, considering in your counry engineers can only earn an average of 300-1000dollars.. that's why more people are trying to migrate to euro countries, after getting the citizenship, they comeback here in the middle east because they will earn much more.. but im only talking about a great majority of companies here in the middle east not necessarily all..

but also, capability for the post is also a factor for you to get high salary.. but again subject to a bracket or salary structure of your company..