You've identified the problem, but not the solution. We must make it illegal for corpos to do labour exploitation in this way and then enforce that law for immigrants and native workers alike. Immigration is good. Creating a two-tiered job market is not. If you just end H1Bs, then many of these jobs will move permanently overseas, there won't be a magical moment of restitution for the aggrieved American tech worker. Unionize if you want to actually make things change for the better for all workers in your industry. You can't post your way out of this.