davidw didn't say H1-Bs. He said "immigrants".
But, since you bring it up...
The legal minimum H1-B salary is based on 'prevailing wage' standards, of which there are many to choose from. Sufficiently so, such that one employer I know was hiring PhD statisticians with 20 years of experience in bioinformatics for 90K/yr. In downtown Cambridge, a block from MIT.
Doesn't that sound like a princely salary for today's senior scientist with a family in Massachusetts to support? Maybe they'll throw in a gym membership at Planet Fitness.
Are you under the impression that current rates of state & local taxation realistically reflect the actual cost of servicing future obligations for services and infrastructure, including pension costs? They don't pay that much more into the system....of course, if Trump set the minimum H1-B salary to 300K nationwide, and allowed for a marginal rate of 65%, that would be a different story.