>They only become immigrants if and when they adjust status and get a green card at which point none of the limitations you listed will apply anymore. But that

>They only become immigrants if and when they adjust status and get a green card at which point none of the limitations you listed will apply anymore. But that process takes years--during that time all of those limitations do apply. And once they do apply, changing employers can reset the application process, adding yet another disincentive to changing jobs. Also since tech salaries are so much higher in the US than nearly anywhere else, most H-1B workers want to stay in the US for a significant length of time (even if they don't plan to stay forever)--during that time it is harder for them to switch jobs than it is for permanent residents.