I'm not sure about the "demand" angle here. Demand is sorted out at the interview stage on a company-level. Once the position has been filled up, it shouldn't be counted towards demand. Hence it should not be subject to lottery. The fact that US has more job opportunities for foreigners compared to, say, Germany in high-tech only means that industry is more thriving in the former. I doubt jobs are created BECAUSE more people wanna move to the US. And by the way, the job search process itself is partly a lottery - it's never 100% about merits.