I don’t think employers have to pay FICA for foreign workers, since they are not eligible for SS/M. The employers also treat the H1B workers like indentured servants — salary, not hourly, and work them more hours than the would an American. They may not even have to provide the same fringe benefits — 401k matching, pensions contributions, health insurance, etc. They can also hire a senior person into an H1B slot where the the job title is “Jr xxxxx” which means a lower “average wage”.
All in, H1B workers might still be considered a “bargain” at 2x the “average” salary of American workers.
I would just make the H1B Visa Application Fee $100K/yr per worker.