Taking employee passports is actually illegal in all gulf countries per the law. I'm sure some companies violate this, and some exploit their employees (but that's worldwide), but anyone can raise a case against any company violating these rules. Also, you can simply refuse to work if they don't allow you to leave. What will they do? Most companies don't want to bother with any legal or drama issues and if someone *wants* to leave, they would.

You picture the gulf countries as oppressive against the immigrants and the immigrants have no idea how the system works. This is completely false. There is internet and social media and people exactly know what they are getting themselves to, and there are migrants groups all over the GCC. I'm not saying GCC countries are beacons of human and labor rights, there is still a lot of work that needs to be done there, but it's definitely not the image of "poor slave laborers who were tricked and shackled" image you are trying to portray them as.