[chimeracoder]

> Doctors in the US are unionized, for the economical sense of the word,

No they are not, for any sense of the word.

> and it is one of the reasons of high cost of health care and under-supply.

No, they are not. Aside from the fact that doctors collectively have about zero control over the total supply, physician earnings account for about 7% of healthcare expenditures. That's a drop in the bucket, even if you reduced that to zero.

> Otherwise, the U.S. would bar foreigners from practicing software engineering, and limit the amount of people that can have a software license.

This much is completely true, and you can look to the incredibly long and xenophobic history of labor unions for evidence of that.