That is why you have to make yourself so valuable that no one can exploit you. You have to be good at what you do and let employers recognize the value you bring to an organization. They can't exploit you that way.Here the workers are paid for the overtime but we (the staff) work extra hours even if it's not in our contract or even if we are not paid for the overtime. Here most industries have such a trend. You can say it's exploitation but we have to do it because we require the job.