What happens if the employer fires them 5 seconds into their first day of employment? Or the employer decides to offer the employee, say, 5 hours of work a year

What happens if the employer fires them 5 seconds into their first day of employment? Or the employer decides to offer the employee, say, 5 hours of work a year? You need some sort of program to verify that the job exists and is "real" in some fashion--this paperwork is the work visa. Don't get me wrong: the US visa polices are a shambolic mess that is counterproductive to its own aims. I'd very much prefer a system that's a lot closer to "employer can sponsor anyone to come into the country if they need to hire from other countries." But what's preventing that isn't the existence of work visas; it's the unwillingness of politicians to advocate for such an immigration system (for which the primary reason I'd suspect boils down to some variant of racism--they feel immigration should be extremely difficult for various undesirable groups).