Well by law they are not supposed to give lower pay or benefits to H1-B or L1 visa workers but the H1B workers do often live at a much lower standard of living in this nation. They have no immigration status and must return to their native land. Now absolutely no one is arguing that they provide a higher standard of work than the americans who they replace (illegally) and who usually have to train them. So clearly it makes no sense to replace an American who is doing the job with an H1-B or L1 unless there is a savings ad such savings are by definition illegal and someone from the hiring company must fill out a sworn staement that the pay is the same as it would be for an American worker and that no Americans were displaced from a job by the hiring of the H1-B worker.
But like WJC said it all depends on the meaning of is.