@Serafiel
You misinterpreted @“aunt bea”'s comment. She wasn’t feeling threatened (nor are any of us) or something by the prospect of a foreigner seeking emploment in the United States, she was simply stating that it’s difficult for international graduates of US schools to obtain work visas, in the event that you were planning to seek employment in the US.
However, I think you need to step back and do a considerable amount of research on your own before you continue to ask questions here. You have shown that you don’t understand how the American university system works, and that’s ok–there’s nothing wrong with that. What is wrong is that you ask questions, receive answers from people who do understand the American university system, then tell them that they’re wrong and refuse to listen to their advice because they don’t confirm what you believe.
Yes, there is a strong relationship between engineering and business, partly because of their analytical and quantitative skills. The MBA is a poor example for you to support your case of studying something different in graduate school because the point of an MBA is to supplement one’s previous experience, whatever industry that previous experience may be in. It is a professional degree.
A hard academic discipline like astronomy is not the same. For a graduate degree in something like astronomy, or virtually any other field, you must have experience in that specific field. I’m not sure what “wacky courses” have to do with anything, but I think you’re conflating undergraduate and graduate studies. Studies at the graduate level are highly specialized and require in-depth study of a particular topic.
No, it doesn’t count. If you want to study astronomy at a graduate level, for example, it will be expected that you will have taken multivariable calculus, differential equations, linear algebra, general physics, classical mechanics, electricity and magnetism, and perhaps other upper level courses in physics. Similarly, I imagine an MA in archaeology/anthropology would have its own set of prerequisites and requirements. If you apply to any graduate program, you’ll be competing for admission against other applicants who will have all this coursework, as well as research experience, in the field. Applying to a graduate program in any field requires you to be focused on that field, and your prior coursework/experience/motivations need to reflect that.