La Frontera Es la Frontera Solamente por la Gente...
Most people writing on the subject have been paying the most attention to social-justice issues as they impact illegal immigrants, citizens of the receiving country, and economics. I'd like to look at the flip side of that coin, and point out one of the other elephants in the room. There are at least two, and one of them seems to be going largely unnoticed. (It's a big room.)
Leaving aside the problems of illegal immigration for a moment, let's look at legal immigration. I think it would be safe to say that most people really have no idea how difficult it really is to become a legal immigrant to an industrialised Western country. I am going to provide facts and figures for Canada because they're easiest to find, being as the Canadian government has some of the best governmental websites in the world.
The three major points I'd like to mention about trying to become a legal immigrant into Canada or elsewhere (based on personal investigation and experience) is that it takes longer than most people realise, it takes more money than most people realise, and it takes more credentials (academic, professional, and vocational) than most people realise.
Speaking of Canada, the wait time to get an immigrant visa can be up to two years, depending on how backlogged the system is, whether you have an immigration lawyer, whether all your paperwork is complete and correct, and other factors. To qualify as a potential immigrant to Canada in the skilled worker class, you must obtain a 67 or better score on the Self-Assessment Test, and then provide documentary evidence to a Citizenship and Immigration Canada officer.
Since it's likely the most common type of application, I'm going to focus on the skilled worker criteria, although there are various other classes of application available. In order to qualify as a skilled worker, you must have a significant amount of education (usually at least a postsecondary degree or diploma), a minimum of two years work experience, marginal fluency in at least one, possibly both official languages, and possibly have arranged employment, and/or family or a spouse in Canada, or who has studied in Canada. (I ran the test on myself, and as a highly-educated, moderately bilingual unmarried person with more than four years' work experience, I'd be eligible to apply with an 80 score without arranged employment.)
However, one of the other criteria immigration officers look at (and which likely disqualifies me as immigrant material, since I'm poorer than the Mouse Interfaith Prayer Breakfast) is, of course, money. I'm given to understand that most immigrants are expected to have a certain sum in cash and assets on hand, sufficient to support themselves for a given period of time upon arrival. (The length of time changes jurisdiction by jurisdiction.) Also, once an immigrant arrives in Canada, he or she will be assessed a "Right of Landing fee" of $975 (this is slated to go down by half in the near future), on top of permanent resident fees of $75 for application processing and $475 applicant fee. (Source: CIC Canada) Right away, that's $550 just to get your paperwork looked at, and another $975 if you get accepted and into the country, for a mind-boggling total of $1525 per immigrant.
Ostensibly this is to defray administrative and assimilation costs. However, if you are unfortunate enough to come from a country where the currency has a low value comparative to the Canadian dollar, coming up with $1525CDN could be a daunting task, even if you make a decent amount of money in your home country.
There is, of course, the kicker. Money. How many of you, Constant Readers, have investments? Any of them overseas? These days, it's getting more and more common for people in the investor class (so to speak) to have a well-diversified portfolio in more than one, maybe several, currencies. A lot of people invest overseas. You can spend your money abroad easier than you can spend a year abroad.
I hear heads rattling as people are nodding as if I'm an idiot. Think about it for a moment: Why do we assume this makes sense?
To reframe the debate in scurrilously Marxist terms, capital is borderless; labour is not.
Personally, I'm relatively well-integrated into the global economy. I've gotten cheques deposited from three different countries, had a person in Korea pay me regularly by wire transfer, and done wire transfers and suchlike to overseas as well. I know what transit codes and SWIFT codes are. I'm not knocking global finance or international business...but it strikes me as kind of agendist that the moneyfolk who deign to run the show for us are vocal opponents of erecting even nominal borders to the flow of capital (like, for instance, the Tobin tax) and are ardent supporters of the "managed commerce" (in the same delightful sense as the US euphemism "managed health care") known as "free trade."
(The exact practical definition of "free trade" is a rant for another time.)
So the upshot is, moving money abroad, that's easy; you can do it in an afternoon, and it'll cost you about 30 minutes with a jamook in a suit and a service charge. Moving yourself abroad takes about two years, multiple reviews, thousands of dollars, and having the right credentials.
You think maybe that's because it's convenient for some people?
Postscript: Illegal immigration is the other option, which may or may not present such significant barriers to entry -- you can fairly easily scoot across a border to Canada, the US, or the UK, and forget to come back...if you're a white native English speaker with a fairly generic name... Even in these times of paranoiac security, you just might be able to slip through the cracks with very little difficulty. (Your mileage may vary, however, likely in proportion to the hue of your skin.)