Firstly, the kinds of businesses who could afford to recruit overseas generally do not lack qualified candidates here in the states. (It’s a big, populous country.)
Secondly because US immigration law is difficult to navigate and there are caps to the number of applicants from many countries.
Lastly, the employer must justify why they are not hiring a US citizen to be able to sponsor a visa. (In most cases if qualified applicants can be found within the country, you won’t be granted the visa.)
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