You are very right to be concerned about international migration, it is a big event, and a big problem for any country.

As you suggested there are many many reasons, but generally PEOPLE ARE NOT HAPPY where they are, that is why they are on the move.

My answer comes by examining my current location and then, my previous location.

My current location: an average town or city in the middle of Canada. It used to be steady at 30,000 people, in a few years it became almost 60,000. People came from everywhere, but mostly from India and China. Some are refugees (could not stay due to war, bad economy or lack of democracy).

In my previous location, Greece: Since the WWII, all the governments are corrupt, there is no democracy (although the people are fiercely democratic). no justice system that works, no future. All dealings are done under the table. The rich pay no taxes, while most people are overtaxed. The European Union has destroyed the country. Greece receives lots of money from EU, however, all of this money ends in private accounts of the rich and the politicians. For example, the PM was elected owing one house, after a few years he has innumerable properties, half the only electricity company and most of the green industry, among other things..On top of that all politicians and bankers are above the law, cannot be prosecuted!

Only a revolution or maybe Trump can fix that problem

Isn't it simply complete failure of some governments (due ideological reasons or sheer incompetence) to protect their borders the dominant factor causing recent mass migration? I mean if mass migration is legal (or technically speaking illegal but that is often not seriously enforced) then why one wouldn't migrate to another country which is richer?

An interesting read from the IOM 2024 report ' World Migration Report'

See link to report https://publications.iom.int/books/world-migration-report-2024

An interesting article from National Geographic that recounts the migration of early humans out of Africa

See Link: https://education.nationalgeographic.org/resource/their-footsteps-human-migration-out-africa/

It is clear, and with hard fact scientific evidence, that humans have been migrating freely for millennia. It is only been in the last six decades or so that this natural human behaviour of migrating has seen considerable hindrance and challenges provided by nation states that require passports, visas, and so forth. Indeed national frontiers and boundaries are a social and political construct which has very little to do with realities on the ground and with human natural behaviour as in fact most of the world’s frontiers and boundaries were drawn up by the very few over the very many and only in recent times: the past two centuries or so. Interestingly birds migrate on a regular basis from country to country and continent to continent and they are definitely not asked for passports and visas.

Indeed The Economist, from a mainly economic perspective, in 2019, provided for an interesting short documentary on migration. The basis of the video is that making migration free, the world would be richer….

See link: https://www.youtube.com/watch?v=fjKYtfpe1a0

An interesting read from the World Bank in 2023 on ' Migrants, refugees and societies'

See Link: https://www.worldbank.org/en/publication/wdr2023