You are quite right. People don't care if uneducated or undereducated immigrants come in to the country --except for a few "nationalists". But over all people don't care or actively support immigration, which is a good thing -bettering people's prospects in life.

However, it is quite evident that professionals are _against_ immigration of other professionals because that directly threatens their professional stability.

So, we know immigration, on the whole is good. We know that immigration from poor countries allows those people to better their lives -at the expense of undereducated (blue collar) locals. But professionals don't quite care, actually, we prefer this since it makes products and services cheaper for us. But once the immigration threatens our lifestyles, then on, no, immigration is bad it drives down wages, it threatens quality of work, it allows exploitation and so on. When push comes to shove, we're all protectionists of varying degrees.

Huh? Medical professionals, lawyers, accountants, actuaries, etc. are all license-based professions. There is a very good reason for this, because a big part of the job is about adhering to important laws, regulations, ethics, etc. A big reason for the non-reciprocity (US-trained doctors cannot practice in many other countries, for example) is that these laws and regulations are not universal. There are some reciprocity arrangements in place, but given how bureaucratic the licensing system is, it is just hard.

You don't have any justification for making programming a license-based profession. You wouldn't want that even if you are an American citizen. It makes things significantly harder and more arbitrary when you have licensing requirements (just look at how hard each of USMLE, CPA, bar, CFA, etc. are, even for US citizens). Engineers, for example, can be licensed, but apart from public contracts in civil, mechanical, or electrical engineering, few employers care if you are a 'P.E.'