The truth of the matter is foreign carriers (EK, EY, QR) have to pay and offer more benefits to attract candidates from elsewhere. Why would anyone want to leave home base and work for them otherwise? ME companies by and large base their compensation packages based on nationality and the disparity is significant. Although this does not apply to pilots generally at the airlines, it is worth mentioning. As an example it's much easier to recruit someone from India because based on home country salary, tax implications and cultural affinity, it's a win-win for the appplicant. This applicant can effectively give themselves a 30- 50% pay raise by just joining. And India is only a 3 hr flight home. Now for some others, it's not as attractive beacuse of the distance from home, tax implications and cultural aspects. For Americans, while their first 100K (approx) of foreign income is excluded from tax, the rest is not. Depending on your deductions you may have a tax liability as well. Also, the non-cash benefits you receive are meant to be declared and may affect your tax picture (housing, schooling, annual ticktets).
At the end of the day it's a balancing act and a personal decision. You might make the equivalent of $400,000 a year BUT in order to make that there are plenty of sacrifices you have to make for QOL, family, interests, citizens rights etc. For some it's a perfect fit, for others it's a debt trap(to support their lifestyle choices) and for the rest it's just a job due to furlough etc. I might add that for many expats, returning home after a few years is not without problems. Some are not able to re-adjust to life at home very easily (comparing everything to how they had it overseas). They find getting back into old relationships a challenge because they haven't been around although new technology (Whatsapp, Facebook) have made things easier. Sometimes they are resented for a variety of reasons. and always, a few return as retreads.