This could be due to political reasons. The EU governments could be requiring the companies to recruit from within EU.
It could be as well due to expediting the hiring process. If you need to get working visa, it would require money and time.
If you put yourself in the recruiter’s shoes or the company who needs to hire, then you should be able to find the answer to your question.
If a company can not find some one within EU and then justify the time and effort to get one from outside, then surely they would do that.
Keep trying in different ways. Hope you find what you want soon. All the best!